ios - 制作成自己的自定义 View 类时， View 不会出现

Question

我正在 Swift 中以编程方式制作一个简单的 View ，我的第一个代码运行得很好:

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .darkGray

        let card:UIView = UIView()
        card.frame = CGRect(x: 38, y: 120, width: 300, height: 300)
        card.backgroundColor = .white
        card.layer.cornerRadius = 10
        card.layer.shadowOpacity = 0.5
        card.layer.shadowOffset = CGSize(width: 0, height: 10)
        card.layer.shadowRadius = 10

        view.addSubview(card)
    }
}

这段代码使这个 View :

但是我想重用该卡，因此我将其放入一个新类(如自定义 View )中，但该卡现在消失了:

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .darkGray

        let card = Card(frame: CGRect(x: 38, y: 120, width: 300, height: 300))

        view.addSubview(card)
    }
}

class Card:UIView {
    var box:UIView = UIView()

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupLayout()
    }

    func setupLayout(){
        box.backgroundColor = .white
        box.layer.cornerRadius = 10
        box.layer.shadowOpacity = 0.5
        box.layer.shadowOffset = CGSize(width: 0, height: 10)
        box.layer.shadowRadius = 10

        addSubview(box)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

你知道第二个代码有什么问题吗？

Answer 1

这样更好:

func setupLayout(){
    box.backgroundColor = .white
    box.layer.cornerRadius = 10
    box.layer.shadowOpacity = 0.5
    box.layer.shadowOffset = CGSize(width: 0, height: 10)
    box.layer.shadowRadius = 10

    box.frame = self.frame
    self.addSubview(box)
}

它自动从初始化器获取帧。