iOS面试败北感悟 | 掘金技术征文

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

日常扯淡

从去年开始, 我就一直有尝试的面试些大公司, 因为对于一个半路出家(非计算机专业), 靠着MJ视频入门的iOS菜鸡玩家, 经过了3年的摸爬滚打, 终于也渐渐的可以做一些简单的前端, 后端, 移动端的交互, 但想要继续深入就感觉瓶颈越发的明显, 基础的薄弱导致很难上升, 所以能够进入一家大型成熟互联网公司就成为了我最近的目标, 原因很简单, 这是最为有效的学习成长的方式.

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
}

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
}

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
}

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.

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
}

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
    }
}

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
}

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))
--- scope of: findMedianSortedArrays ---
500045.0
500045.0
500045.0
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))
--- scope of: findMedianSortedArrays ---
499665.5
499665.5
499665.5
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

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

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

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 { 

}

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UIViewsizeToFit么, 你怎么不实现sizeThatFits, 你是完全不会用吧... 你知道UIButtonAutoLayout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? setBackgroundImagesetImageEdgeInsets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
        }
    }
}

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

测试对比

我们用自己自实现的ButtonUIButton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()
    }
}
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()

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()
    }

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()

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()

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()

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()

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)

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()

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()

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()

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()

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()

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()

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()

这道题还没有实现的就是AutoLayoutEdgeInsets, 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UIImageViewUILabel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
    }()

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
    }

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AutoLayoutEdgeInsets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
    }

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
        }
    }

3.布局时判断即可

    override func layoutSubviews() {
        super.layoutSubviews()

        if createdFromNib {
            frame.size = intrinsicContentSize
        }
        ...
   }

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)

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…

掘金技术征文链接👉 juejin.im/post/5aaf2a…

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