2020 — iOS 面试败北感悟

iOSer

关注

发布于: 2021 年 01 月 05 日

日常扯淡

去年7月, 第一次面试大公司: 饿了么, 收到大公司的召唤非常的兴奋, 觉得自己翻身的机会终于要来了, 兴冲冲的跑去面试, 以为会和一般初级iOS面试的题目相同, 没有做任何的准备, 其实也不知道准备什么, 记得那时候聊的是:

UI 方面: 如何避免卡顿掉帧, 异步渲染.
性能方面: 性能优化, Vsync, CPU / GPU
网络方面: 如何进行请求缓存策略.
安全方面: lild重签名, Mach-O.
前端方面: 如何避免DOM重绘.
后端方面: 如何进行负载均衡的处理.

还有一些极端的情况, 由于时间久远已经记不太清了, 反正这次面试给我的感觉就是, 靠... 我简直就是个垃圾啊~ 当时记得内推我的架构师建议我扎实一下iOS的基本功, 然后就推荐了基本书: 计算机网络, 操作系统原理, HTTP权威指南, TCP/IP权威指南, 深入解析Max OS X & iOS 操作系统... 这些书, 除了HTTP权威指南我咬着牙看完了, 其他的对于我来说简直就是天书, 根本消化不良啊.

去年12月, 第二次面试大公司: 京东, 由于有了上一次的经验, 我变得非常的淡定, 知道自己肯定会被大公司所淘汰, 和优等专业生有着不可逾越的天堑, 比较吃惊的是, 进入京东的大楼需要用身份证换取临时门禁... 那时候的面试题就比饿了么的柔和的多了, 虽然当时还是回答不出.

Runtime: isa, 消息转发, 弱引用表.
Runloop: mode, timer.
Block: __block, __forwording.
Property: assign, weak, copy.
Category: assoc, load

现在想想, 这 TM 才是面试iOS啊, 只可惜, 那时候并不具备这些知识, 可惜了了. 之后我就对C++, ASM, Linux, 这三方面进行了学习, 也学习了些MACH-O, 逆向的相关的知识, 以备后面的面试机会.

第三次就是这周三面试第二梯队了, 我准备了所有我能够准备的面试题内容, 底层原理, 逆向安全, 多线程与锁, 内存布局, UI性能优化等, 果不其然, 足足1个小时的电话面试, 我轻松通过, 问的就是些我准备好的底层知识, 让我觉得机会终于来了, 可是.... 当我现场面试后... 题目全部是上机题...

设计一个网络框架, 如何进行不同数据解析的设计(header, body), 并能够进行自定义, 重连机制如何处理, 状态码错误转发机制的处理, 如何避免回调地狱, 实现Promise的自实现.
根据UIControl实现UIButton....
找到两个排序数组的中位数...
pow(double, double)函数的自实现....

果然,网络, UI, 算法... 好吧, 第一次做上机题, 瞬间就蒙了... 然后就是面试官在旁边不停的笑... 不停的笑... 可能是他对我友好的一种方式吧... 最后的面试结论是, 我的知识面还是比较广的, 做过的东西也是挺多的, 但是在知识深度方面还是比较欠缺.

后来得知, 他们招聘的是技术专家的职级, 觉得我的技术水平达不到要求, 不能给与录取, 当然被拒我是当场就知道了, 也觉得美团和饿了么的两次面试经历都和我的水平相差甚远... 可是, 我只是想进入大公司学习, 就一定要成为专家才行么? 现在初中高级, 资深都不需要了, 直接专家么..., 我的猎头朋友和我说, 3-1的级别就是对标阿里P6/P7, 我选择去死啊.....

有了这次的面试经验后, 我的策略也发生了改变, 不再追求大公司的光环了, 做人开心一点不好么, 非要像机器一样思考? 活的像个算法一样是不是感觉缺少了些重要的东西? 和朋友们吹吹牛逼的日子不快活么, 偏要用功学习? 这里想到了最近听到的两句话, 最好的产品体验就是要让用户不用思考, 认知即痛苦, 无知即极乐, 人真是矛盾, 价值观的一念之差, 差之毫厘失之千里啊....

面试题 1 自实现 pow(double, double)

这道题目上机的时候非常的蒙, 因为幂是double, 完全不知道如何下手, 面试官就降低难度使用整型.

解法 1

func _pow_1(_ base: Int, _ exponent: Int) -> Int {
    if exponent < 0 {        return 0    }    if exponent == 0 {        return 0    }    if exponent == 1 {        return base    }
    var result = base    for _ in 1..<exponent {        result *= base    }    return result}

复制代码

然后, 第一次做算法题的我, 只能想到通过最为粗糙的办法解答, 就是一个循环, 我也知道这不是面试官所期许的答案, 但这有什么办法呢...

解法 2

func _pow_2(_ base: Double, _ exponent: Int) -> Double {
    if exponent < 0 {        return 0    }    if exponent == 0 {        return 0    }    var ans:Double = 1, last_pow = base, exp = exponent
    while exp > 0 {        if (exp & 1) != 0 {            ans = ans * last_pow        }        exp = exp >> 1        last_pow = last_pow * last_pow    }    return ans}

复制代码

这个是我在网上翻阅资料后的另一种看似比较好的解答方式.

解法 3

func _pow_3(_ base: Double, _ exponent: Int) -> Double {
    var isNegative = false    var exp = exponent    if exp < 0 {        isNegative = true        exp = -exp    }    let result = _pow_2(base, exp)    return isNegative ? 1 / result : result}

复制代码

这个仅仅是加了一个负值判断.... 但是幂是double的仍然是毫无头绪, 需要请大佬和大神不吝赐教.

如果你正在跳槽或者正准备跳槽不妨动动小手，添加一下咱们的交流群1012951431来获取一份详细的大厂面试资料为你的跳槽多添一份保障。

面试题 2 findMedianSortedArrays

这是一道 LeetCode 的原题, 但是我至今还没有刷过算法题库... 也是平生第一次面试的时候遇到算法题. 题目的意思是找到两个排序数组的中位数.

解法 1

func findMedianSortedArrays_1(_ array1: [Int], _ array2: [Int]) -> Double {
    var array = [Int]()    array.append(contentsOf: array1)    array.append(contentsOf: array2)
    quickSort(list: &array)
    let b = array.count % 2    let c = array.count    var result = 0.0;    if  b == 1  {        result = Double(array[c / 2])    } else {        let n1 = array[c / 2 - 1]        let n2 = array[c / 2]        result = Double((n1 + n2)) / 2.0    }
    return result}

复制代码

第一次做算法题, 只能无视算法复杂度, 能够完成就算是不错了, 要什么自行车...

解法 2

func findMedianSortedArrays_2(_ array1: [Int], _ array2: [Int]) -> Double {
    let c1 = array1.count, c2 = array2.count    var a1 = array1, a2 = array2    if c1 <= 0 && c2 <= 0 {        return 0.0    }
    func findKth(_ nums1: inout [Int], i: Int, _ nums2: inout [Int], j: Int, k: Int) -> Double {        if nums1.count - i > nums2.count - j {            return findKth(&nums2, i: j, &nums1, j: i, k: k)        }        if nums1.count == i {            return Double(nums2[j + k - 1])        }        if k == 1 {            return Double(min(nums1[i], nums2[j]))        }        let pa = min(i + k / 2, nums1.count), pb = j + k - pa + i        if nums1[pa - 1] < nums2[pb - 1] {            return findKth(&nums1, i: pa, &nums2, j: j, k: k - pa + i)        } else if nums1[pa - 1] > nums2[pb - 1] {            return findKth(&nums1, i: i, &nums2, j: pb, k: k - pb + j)        } else {            return Double(nums1[pa - 1])        }    }
    let total = c1 + c2    if total % 2 == 1 {        return findKth(&a1, i: 0, &a2, j: 0, k: total / 2 + 1)    } else {        return (findKth(&a1, i: 0, &a2, j: 0, k: total / 2) + findKth(&a1, i: 0, &a2, j: 0, k: total / 2 + 1)) / 2.0    }}

复制代码

这个是我在网上查资料的时候的答案... 还没理清是个什么思路, 反正面试官提示分而治之, 掐头去尾... 也不知道是不是最优算法.

解法 3

func findMedianSortedArrays_3(_ array1: [Int], _ array2: [Int]) -> Double {
    let total = array1.count + array2.count    let index = total / 2    let count = array1.count < array2.count ? array2.count : array1.count    var array = [Int]()
    var i = 0, j = 0;    for _ in 0...count {        if array.count >= index + 1 {            break        }        if array1[i] < array2[j] {            array.append(array1[i])            i += 1        } else {            array.append(array2[j])            j += 1        }    }    return total % 2 == 1 ? Double(array[index]) : Double(array[index] + array[index - 1]) * 0.5}

复制代码

这个是请教霜神(@halfrost-一缕殇流化隐半边冰霜)后给的思路, 的确很好实现. 但霜神谦虚的说不是最优解....

奇数测试

var array1 = randomList(1000001)var array2 = randomList(1000000)quickSort(list: &array1)quickSort(list: &array2)print(findMedianSortedArrays_1(array1, array2))print(findMedianSortedArrays_2(array1, array2))print(findMedianSortedArrays_3(array1, array2))

复制代码

--- scope of: findMedianSortedArrays ---500045.0500045.0500045.0

复制代码

偶数测试

var array1 = randomList(1000001)var array2 = randomList(1000000)quickSort(list: &array1)quickSort(list: &array2)print(findMedianSortedArrays_1(array1, array2))print(findMedianSortedArrays_2(array1, array2))print(findMedianSortedArrays_3(array1, array2))

复制代码

--- scope of: findMedianSortedArrays ---499665.5499665.5499665.5

复制代码

耗时比较

--- scope of: findMedianSortedArrays_1 ---timing: 2.50845623016357--- scope of: findMedianSortedArrays_2 ---timing: 1.28746032714844e-05--- scope of: findMedianSortedArrays_3 ---timing: 0.0358490943908691

复制代码

可以看出网上查资料的答案是三种解法里性能最高的算法, 霜神的思路和网上的答案差了三个数量级, 而我写的差了五个数量级.... 果然我写的果然是最为垃圾的算法....

解法 4

@discardableResult func findMedianSortedArrays_4(_ array1: [Int], _ array2: [Int]) -> Double {
    if array1.count == 0 {        if array2.count % 2 == 1 {            return Double(array2[array2.count / 2])        } else {            return Double(array2[array2.count / 2] + array2[array2.count / 2 - 1]) * 0.5        }    } else if array2.count == 0 {        if array1.count % 2 == 1 {            return Double(array1[array1.count / 2])        } else {            return Double(array1[array1.count / 2] + array1[array1.count / 2 - 1]) * 0.5        }    }
    let total = array1.count + array2.count    let count = array1.count < array2.count ? array1.count : array2.count    let odd = total % 2 == 1
    var i = 0, j = 0, f = 1, m1 = 0.0, m2 = 0.0, result = 0.0;    for _ in 0...count {        if odd { array1[i] < array2[j] ? (i += 1) : (j += 1) }        if f >= total / 2 {            if odd {                result = array1[i] < array2[j] ? Double(array1[i]) : Double(array2[j])            } else {                if array1[i] < array2[j] {                    m1 = Double(array1[i])                    if (i + 1) < array1.count && array1[i + 1] < array2[j] {                        m2 = Double(array1[i + 1])                    } else {                        m2 = Double(array2[j])                    }                } else {                    m1 = Double(array2[j])                    if (j + 1) < array2.count && array2[j + 1] < array1[i] {                        m2 = Double(array2[j + 1])                    } else {                        m2 = Double(array1[i])                    }                }                result = (m1 + m2) * 0.5            }            break        }        if !odd { array1[i] < array2[j] ? (i += 1) : (j += 1) }        f += 1    }    return result}

复制代码

--- scope of: findMedianSortedArrays_3 ---timing: 0.0358932018280029--- scope of: findMedianSortedArrays_4 ---timing: 0.0241639614105225

复制代码

沿着霜神的思路和面试官给的提示, 给出了上面的算法, 但是解法3的数量级是相同的

如果你正在跳槽或者正准备跳槽不妨动动小手，添加一下咱们的交流群1012951431来获取一份详细的大厂面试资料为你的跳槽多添一份保障。

面试题 3 UIContorl -> UIButton

protocol ButtonInterface {    func setTitle(_ title: String);    func setTitleColor(_ titleColor: UIColor);    func setTitleEdgeInsets(_ edgeInsets: UIEdgeInsets);    func setImage(_ image: UIImage);    func setBackgroundImage(_ image: UIImage);    func setImageEdgeInsets(_ edgeInsets: UIEdgeInsets);}
class Button: UIControl, ButtonInterface { 
}

复制代码

以上就是面试时候的原题, 一开始根本不知道是要让我做些什么, 说是只要让我把上面的方法全部实现就好了, 就像实现一个自己的 UIButton... 一开始, 我以为是要我用CALayer来实现, 吓的我瑟瑟发抖... 还好不是... 然后, 我就按照自己平时自定义控件的写法, 写了一个UIImageView, 一个UILabel, 然后布局赋值... 就看到面试官对着我笑着说, 你以为这道题这么简单么... 这么简单么...

然后说, 你知道UIButton setTitle的时候才会创建UILabel, setImage的时候才会创建UIImageView, 你为什么吧frame给写死... 不知道UIView有sizeToFit么, 你怎么不实现sizeThatFits, 你是完全不会用吧... 你知道UIButton用AutoLayout布局的时候只要设置origin坐标, 宽高就可以自适应了, 你自定义的时候怎么不实现呢? setBackgroundImage和setImageEdgeInsets你就不要做了吧, 反正你也不会...

我想说的是,谁没事放着UIButton不用, 用UIContorl这种东西... 就为了一个target-action的设计模式么... 我每次在想思路的时候一直打断我, 可能这是面试官的一种策略吧... 算了不吐槽了, 还是尽力实现吧.

import UIKit
protocol ButtonInterface {    func setTitle(_ title: String);    func setTitleColor(_ titleColor: UIColor);    func setTitleEdgeInsets(_ edgeInsets: UIEdgeInsets);    func setImage(_ image: UIImage);    func setBackgroundImage(_ image: UIImage);    func setImageEdgeInsets(_ edgeInsets: UIEdgeInsets);}
class Button: UIControl, ButtonInterface {
    lazy var titleLabel: UILabel = UILabel()    lazy var imageView: UIImageView = UIImageView()    lazy var backgroundImageView: UIImageView = UIImageView()
    var titleLabelIsCreated = false    var imageViewIsCreated = false    var backgroundImageViewCreated = false
    internal func setTitle(_ text: String) {        if !titleLabelIsCreated {            addSubview(titleLabel)            titleLabelIsCreated = true        }        titleLabel.text = text    }
    internal func setTitleColor(_ textColor: UIColor) {        if !titleLabelIsCreated {            return        }        titleLabel.textColor = textColor    }
    internal func setTitleEdgeInsets(_ edgeInsets: UIEdgeInsets) {        if !titleLabelIsCreated {            return        }    }
    internal func setImage(_ image: UIImage) {        if !imageViewIsCreated {            addSubview(imageView)            imageViewIsCreated = true        }        imageView.image = image    }
    internal func setBackgroundImage(_ image: UIImage) {        if !backgroundImageViewCreated {            addSubview(backgroundImageView)            insertSubview(backgroundImageView, at: 0)            backgroundImageViewCreated = true        }        backgroundImageView.image = image    }
    internal func setImageEdgeInsets(_ edgeInsets: UIEdgeInsets) {        if !imageViewIsCreated {            return        }    }
    override func sizeThatFits(_ size: CGSize) -> CGSize {        if titleLabelIsCreated && !imageViewIsCreated && !backgroundImageViewCreated {            let text: NSString? = titleLabel.text as NSString?            let titleLabelW: CGFloat = text?.boundingRect(with: CGSize(width: CGFloat(MAXFLOAT), height: bounds.height), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.width ?? 0.0            let titleLabelH: CGFloat = text?.boundingRect(with: CGSize(width: titleLabelW, height: CGFloat(MAXFLOAT)), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.height ?? 0.0            return CGSize(width: titleLabelW, height: titleLabelH + 10)        } else if !titleLabelIsCreated && imageViewIsCreated {            return imageView.image?.size ?? CGSize.zero        } else if titleLabelIsCreated && imageViewIsCreated {            let text: NSString? = titleLabel.text as NSString?            let titleLabelW: CGFloat = text?.boundingRect(with: CGSize(width: CGFloat(MAXFLOAT), height: bounds.height), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.width ?? 0.0            let titleLabelH: CGFloat = text?.boundingRect(with: CGSize(width: titleLabelW, height: CGFloat(MAXFLOAT)), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.height ?? 0.0            let imageViewW: CGFloat = imageView.image?.size.width ?? 0.0            let imageViewH: CGFloat = imageView.image?.size.height ?? 0.0            return CGSize(width: titleLabelW + imageViewW, height: imageViewH > titleLabelH ? imageViewH : titleLabelH)        } else {            return backgroundImageView.image?.size ?? CGSize.zero        }    }
    override func layoutSubviews() {        super.layoutSubviews()
        if titleLabelIsCreated && !imageViewIsCreated {            titleLabel.frame = bounds            titleLabel.textAlignment = .center        } else if !titleLabelIsCreated && imageViewIsCreated {            let y: CGFloat = 0;            let width: CGFloat = imageView.image?.size.width ?? 0;            let x: CGFloat = (bounds.width - width) * 0.5;            let height: CGFloat = bounds.height;            imageView.frame = CGRect(x: x, y: y, width: width, height: height)        } else if titleLabelIsCreated && imageViewIsCreated {            let imageViewY: CGFloat = 0;            let imageViewW: CGFloat = imageView.image?.size.width ?? 0;            let imageViewH: CGFloat = bounds.height;            let text: NSString? = titleLabel.text as NSString?            let titleLabelW: CGFloat = text?.boundingRect(with: CGSize(width: CGFloat(MAXFLOAT), height: bounds.height), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.width ?? 0.0            let titleLabelH: CGFloat = text?.boundingRect(with: CGSize(width: titleLabelW, height: CGFloat(MAXFLOAT)), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.height ?? 0.0            let imageViewX: CGFloat = (bounds.width - imageViewW - titleLabelW) * 0.5;            let titleLabelX: CGFloat = imageViewX + imageViewW            let titleLabelY = (bounds.height - titleLabelH) * 0.5            titleLabel.frame = CGRect(x: titleLabelX, y: titleLabelY, width: titleLabelW, height: titleLabelH)            imageView.frame = CGRect(x: imageViewX, y: imageViewY, width: imageViewW, height: imageViewH)        }
        if backgroundImageViewCreated {            backgroundImageView.frame = bounds        }    }}

复制代码

虽然实现了部分的功能, 但是AutoLayout和EdgeInsets的功能还是没有思路, 还请各位大佬解惑.

如果你正在跳槽或者正准备跳槽不妨动动小手，添加一下咱们的交流群1012951431来获取一份详细的大厂面试资料为你的跳槽多添一份保障。

测试对比

我们用自己自实现的Button和UIButton进行对比.

class ViewController: UIViewController {
    override func loadView() {        super.loadView();
        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)        uibutton.setImage(UIImage(named: "avatar"), for: .normal)        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        button.setImage(UIImage(named: "avatar") ?? UIImage());        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)        button.sizeToFit()    }}

复制代码

zero impl


        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)//        uibutton.setTitle("github.com/coderZsq", for: .normal)//        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)//        uibutton.setImage(UIImage(named: "avatar"), for: .normal)//        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)//        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)//        button.setTitle("github.com/coderZsq")//        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))//        button.setImage(UIImage(named: "avatar") ?? UIImage());//        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)//        button.sizeToFit()

复制代码

setTitle && setTitleColor

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)//        uibutton.setImage(UIImage(named: "avatar"), for: .normal)//        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)//        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))//        button.setImage(UIImage(named: "avatar") ?? UIImage());//        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)//        button.sizeToFit()    }

复制代码

setTitle && setTitleColor && sizeToFit

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)//        uibutton.setImage(UIImage(named: "avatar"), for: .normal)//        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))//        button.setImage(UIImage(named: "avatar") ?? UIImage());//        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)        button.sizeToFit()

复制代码

setImage

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)//        uibutton.setTitle("github.com/coderZsq", for: .normal)//        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)        uibutton.setImage(UIImage(named: "avatar"), for: .normal)//        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)//        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)//        button.setTitle("github.com/coderZsq")//        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        button.setImage(UIImage(named: "avatar") ?? UIImage());//        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)//        button.sizeToFit()

复制代码

setImage && sizeToFit

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)//        uibutton.setTitle("github.com/coderZsq", for: .normal)//        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)        uibutton.setImage(UIImage(named: "avatar"), for: .normal)//        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)//        button.setTitle("github.com/coderZsq")//        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        button.setImage(UIImage(named: "avatar") ?? UIImage());//        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)        button.sizeToFit()

复制代码

setBackgroundImage

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)//        uibutton.setTitle("github.com/coderZsq", for: .normal)//        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)//        uibutton.setImage(UIImage(named: "avatar"), for: .normal)        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)//        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)//        button.setTitle("github.com/coderZsq")//        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))//        button.setImage(UIImage(named: "avatar") ?? UIImage());        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)//        button.sizeToFit()

复制代码

这里, 我们看到和系统的实现不一样, 因为我直接在渲染(display)设置了bitmap, 而不是像系统添加了一个新的view. 这样的性能消耗会少些... (以修改为了下面的问题)

如果你正在跳槽或者正准备跳槽不妨动动小手，添加一下咱们的交流群1012951431来获取一份详细的大厂面试资料为你的跳槽多添一份保障。

setBackgroundImage && sizeToFit

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)//        uibutton.setTitle("github.com/coderZsq", for: .normal)//        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)//        uibutton.setImage(UIImage(named: "avatar"), for: .normal)        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)//        button.setTitle("github.com/coderZsq")//        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))//        button.setImage(UIImage(named: "avatar") ?? UIImage());        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)        button.sizeToFit()

复制代码

setTitle && setTitleColor && setImage

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)        uibutton.setImage(UIImage(named: "avatar"), for: .normal)//        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)//        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        button.setImage(UIImage(named: "avatar") ?? UIImage());//        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)//        button.sizeToFit()

复制代码

setTitle && setTitleColor && setImage && sizeToFit

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)        uibutton.setImage(UIImage(named: "avatar"), for: .normal)//        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        button.setImage(UIImage(named: "avatar") ?? UIImage());//        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)        button.sizeToFit()

复制代码

setTitle && setTitleColor && setBackgroundImage


        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)//        uibutton.setImage(UIImage(named: "avatar"), for: .normal)        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)//        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))//        button.setImage(UIImage(named: "avatar") ?? UIImage());        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)//        button.sizeToFit()

复制代码

如果你正在跳槽或者正准备跳槽不妨动动小手，添加一下咱们的交流群1012951431来获取一份详细的大厂面试资料为你的跳槽多添一份保障。

setTitle && setTitleColor && setBackgroundImage && sizeToFit

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)//        uibutton.setImage(UIImage(named: "avatar"), for: .normal)        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))//        button.setImage(UIImage(named: "avatar") ?? UIImage());        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)        button.sizeToFit()

复制代码

setTitle && setTitleColor && setImage && setBackgroundImage

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)        uibutton.setImage(UIImage(named: "avatar"), for: .normal)        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)//        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        button.setImage(UIImage(named: "avatar") ?? UIImage());        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)//        button.sizeToFit()

复制代码

setTitle && setTitleColor && setImage && setBackgroundImage && sizeToFit

        let uibutton = UIButton()        uibutton.layer.borderWidth = 1        uibutton.layer.borderColor = UIColor.black.cgColor
        uibutton.frame = CGRect(x: 0, y: 100, width: view.bounds.width, height: 40)        uibutton.setTitle("github.com/coderZsq", for: .normal)        uibutton.setTitleColor(.red, for: .normal)//        uibutton.titleEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 0)        uibutton.setImage(UIImage(named: "avatar"), for: .normal)        uibutton.setBackgroundImage(UIImage(named: "avatar"), for: .normal)//        uibutton.imageEdgeInsets = UIEdgeInsetsMake(-10, -10, -10, -10)        view.addSubview(uibutton)        uibutton.sizeToFit()
        let button = Button()        button.layer.borderWidth = 1        button.layer.borderColor = UIColor.black.cgColor
        button.frame = CGRect(x: 0, y: 350, width: view.bounds.width, height: 40)        button.setTitle("github.com/coderZsq")        button.setTitleColor(.red)//        button.setTitleEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        button.setImage(UIImage(named: "avatar") ?? UIImage());        button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())//        button.setImageEdgeInsets(UIEdgeInsetsMake(0, 0, 0, 0))        view.addSubview(button)        button.sizeToFit()

复制代码

这道题还没有实现的就是AutoLayout和EdgeInsets, 还有就是在sizeToFit算的最佳尺寸和系统的最佳尺寸有细微出入, 还有就是UIImageView和UILabel的先后加载的问题.

update

    lazy var titleLabel: UILabel =  {        let titleLabel = UILabel()        titleLabel.font = UIFont.systemFont(ofSize: 18)        titleLabel.textAlignment = .center        return titleLabel    }()

复制代码

对于在sizeToFit算的最佳尺寸和系统的最佳尺寸有细微出入 这个问题是UILabel的默认系统字体大小是17, 而UIButton中的titleLabel的字体大小是18.

    internal func setImage(_ image: UIImage) {        if !imageViewIsCreated {            addSubview(imageView)            if titleLabelIsCreated {                insertSubview(imageView, belowSubview: titleLabel)            }            imageViewIsCreated = true        }        imageView.image = image    }

复制代码

对于UIImageView和UILabel的先后加载的问题, 需要在setImage时判断titleLabel是否存在即可

现已达到完全相同, 接下来就是要解决AutoLayout和EdgeInsets的问题.

update2

通过 nib 进行创建.. 谢谢@梦痕_Lee提供的思路.

实现方法:

1.判断是否是从 nib 中创建

    var createdFromNib = false
    override init(frame: CGRect) {        super.init(frame: frame)    }
    required init?(coder aDecoder: NSCoder) {        super.init(coder: aDecoder)        createdFromNib = true    }

复制代码

2.重写系统实现函数intrinsicContentSize并返回最佳尺寸

    override var intrinsicContentSize: CGSize {        return bestSize()    }
    func bestSize() -> CGSize {        if titleLabelIsCreated && !imageViewIsCreated && !backgroundImageViewCreated {            let text: NSString? = titleLabel.text as NSString?            let titleLabelW: CGFloat = text?.boundingRect(with: CGSize(width: CGFloat(MAXFLOAT), height: bounds.height), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.width ?? 0.0            let titleLabelH: CGFloat = text?.boundingRect(with: CGSize(width: titleLabelW, height: CGFloat(MAXFLOAT)), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.height ?? 0.0            return CGSize(width: titleLabelW, height: titleLabelH + 10)        } else if !titleLabelIsCreated && imageViewIsCreated {            return imageView.image?.size ?? CGSize.zero        } else if titleLabelIsCreated && imageViewIsCreated {            let text: NSString? = titleLabel.text as NSString?            let titleLabelW: CGFloat = text?.boundingRect(with: CGSize(width: CGFloat(MAXFLOAT), height: bounds.height), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.width ?? 0.0            let titleLabelH: CGFloat = text?.boundingRect(with: CGSize(width: titleLabelW, height: CGFloat(MAXFLOAT)), options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : titleLabel.font], context: nil).size.height ?? 0.0            let imageViewW: CGFloat = imageView.image?.size.width ?? 0.0            let imageViewH: CGFloat = imageView.image?.size.height ?? 0.0            return CGSize(width: titleLabelW + imageViewW, height: imageViewH > titleLabelH ? imageViewH : titleLabelH)        } else {            return backgroundImageView.image?.size ?? CGSize.zero        }    }

复制代码

3.布局时判断即可

    override func layoutSubviews() {        super.layoutSubviews()
        if createdFromNib {            frame.size = intrinsicContentSize        }        ...   }

复制代码

4.测试一下, 不加 sizetofit

        nib_button.layer.borderWidth = 1        nib_button.layer.borderColor = UIColor.black.cgColor
        nib_button.setTitle("github.com/coderZsq")        nib_button.setTitleColor(.red)//        nib_button.setTitleEdgeInsets(.zero)        nib_button.setImage(UIImage(named: "avatar") ?? UIImage())//        nib_button.setBackgroundImage(UIImage(named: "avatar") ?? UIImage())        nib_button.setImageEdgeInsets(.zero)

复制代码

一样的完美, 攻克了AutoLayout, 接下来就是EdgeInsets啦~~~

update3

一直理解错了, intrinsicContentSize这个方法是在添加约束后生效, 不管是nib还是手动约束, 都会生效.

所以update2中只需实现第二步即可, 并不需要其他的判断.

面试题 4 网络架构实现

这道题真是戳中我的软肋, 网络与多线程是我最为薄弱的地方, 现在对线程的理解应该已经不错了, 但是网络还是有所欠缺的, 所以, 我会在今后学习Linux和精读AFNetWorking && SDWebImage后, 自己写一个网络架构来进行自我提升.

面试总结

对于两道算法题, 我没有什么太多想讲的, 技不如人吧, 可是算法题这种东西在iOS上用处其实不是很大, 我就不信那些没有刷过算法题的同学, 面对一道从没有见过的算法题能够一下子从容的写出最优解的. 还有就是UI的那道题目, 坑吧, 谁会去放着好好的现成的不用, 去恶心自己, 还一定要一样... 我都问过面试官好几遍, 到底想要做什么功能... 回答只有, 我不在乎你怎么写, 只要和系统的一样就好了.... 产品附体了么....

好吧... 技不如人, 被挂了也是理所当然... 不会找什么借口... 听美团的朋友说, 现在只招技术专家, 其他低职级的名额紧缩都不招了... 诶... 随缘吧...

最后本文中所有的源码都可以在 github 上找到:

GitHub Repo：coderZsq.target.swift
Follow: coderZsq · GitHub
Resume: coderzsq.github.io/coderZsq.we…

资料推荐

如果你正在跳槽或者正准备跳槽不妨动动小手，添加一下咱们的交流群1012951431来获取一份详细的大厂面试资料为你的跳槽多添一份保障。

发布于: 2021 年 01 月 05 日阅读数: 53

iOSer

关注

微信搜索添加微信 mayday1739 进微信群哦 2020.09.12 加入

更多大厂面试资料进企鹅群931542608

发布

暂无评论

创作场景

2020 — iOS 面试败北感悟

日常扯淡

面试题 1 自实现 pow(double, double)

解法 1

解法 2

解法 3

面试题 2 findMedianSortedArrays

解法 1

解法 2

解法 3

奇数测试

偶数测试

耗时比较

解法 4

面试题 3 UIContorl -> UIButton

测试对比

zero impl

setTitle && setTitleColor

setTitle && setTitleColor && sizeToFit

setImage

setImage && sizeToFit

setBackgroundImage

setBackgroundImage && sizeToFit

setTitle && setTitleColor && setImage

setTitle && setTitleColor && setImage && sizeToFit

setTitle && setTitleColor && setBackgroundImage

setTitle && setTitleColor && setBackgroundImage && sizeToFit

setTitle && setTitleColor && setImage && setBackgroundImage

setTitle && setTitleColor && setImage && setBackgroundImage && sizeToFit

update

update2

update3

面试题 4 网络架构实现

面试总结

资料推荐

iOSer

评论