从未出现在视图中的子类创建按钮

Question

谁能解释一下为什么下面的代码没有在我的视图中放置一个按钮？

按钮Class

class CustomButton: UIButton {

    var button = UIButton()

    func makeButton() {
        button.frame = CGRect(x: 0, y: 0, width: 200, height: 200)
        button.center = self.center
        button.setTitle("PRESS", for: .normal)
        button.backgroundColor = UIColor.red
        button.addTarget(self, action: #selector(ViewController.buttonPressed), for: .touchUpInside)
        self.addSubview(button)
    }
}

主要Class

class ViewController: UIViewController {

    var button: CustomButton?

    override func viewDidLoad() {
        super.viewDidLoad()

        button?.makeButton()
    }

    @objc func buttonPressed() {
        print("woohoo!")
    }
}

Answer 1

您需要完全重做 CustomButton class。它不应该有 button 属性。它应该自行初始化。

并且目标的设置属于视图控制器，而不是按钮class。

更新的按钮代码：

class CustomButton: UIButton {
    init() {
        super.init(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        setTitle("PRESS", for: .normal)
        backgroundColor = UIColor.red
    }

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

更新视图控制器：

class ViewController: UIViewController {
    var button = CustomButton()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.addSubview(button)
        button.addTarget(self, action: #selector(buttonPressed), for: .touchUpInside)
    }

    @objc func buttonPressed() {
        print("woohoo!")
    }
}

从未出现在视图中的子类创建按钮

Creating a button from a subclass not appearing in view

subclass

uibutton

swift