无法在另一个类中设置 UIButton 目标？

Question

我正在尝试构建一个自定义控制器来管理一组Uibuttons。

viewController设置按钮并放置：

override func viewDidLoad() {
    super.viewDidLoad()
    let button1 = UIButton()
    button1.setTitle("Button 1", for: UIControlState.normal)
    button1.setTitleColor(UIColor.blue, for: UIControlState.normal)
    button1.frame.origin.y = 120
    button1.sizeToFit()
    button1.isUserInteractionEnabled = true
    let button2 = UIButton()
    button2.setTitle("Button 2", for: UIControlState.normal)
    button2.setTitleColor(UIColor.blue, for: UIControlState.normal)
    button2.frame.origin.y = 160
    button2.sizeToFit()

    let button3 = UIButton()
    button3.setTitle("Button 3", for: UIControlState.normal)
    button3.setTitleColor(UIColor.blue, for: UIControlState.normal)
    button3.frame.origin.y = 190
    button3.sizeToFit()
    let controller = CustomButtonController(buttons: button1, button2, button3)
    self.view.addSubview(button1)
    self.view.addSubview(button2)
    self.view.addSubview(button3) }

CustomButtonController：

class CustomButtonController : NSObject {
    init(buttons: UIButton...) {
        super.init()
        for aButton in buttons {
            aButton.addTarget(self, action: #selector(pressed(_:)), for: UIControlEvents.touchUpInside)
        }
    }
    func pressed(_ sender: UIButton) {
        print("Press received in CustomButtonController")
        //Never gets called
    }
}

如果我在ViewController内部的按钮上使用addTarget方法，则可以正常工作。知道为什么我们不能这样的uibutton添加目标？谢谢

Answer 1

您正在创建CustomButtonController作为viewDidLoad中的局部常数。viewDidLoad返回后，该对象即将释放，因此不再处理按钮taps。

您需要声明一个实例属性以保存控制器实例：

var controller: CustomButtonController!
override func viewDidLoad() {
    super.viewDidLoad()
    let button1 = UIButton()
    button1.setTitle("Button 1", for: UIControlState.normal)
    button1.setTitleColor(UIColor.blue, for: UIControlState.normal)
    button1.frame.origin.y = 120
    button1.sizeToFit()
    button1.isUserInteractionEnabled = true
    let button2 = UIButton()
    button2.setTitle("Button 2", for: UIControlState.normal)
    button2.setTitleColor(UIColor.blue, for: UIControlState.normal)
    button2.frame.origin.y = 160
    button2.sizeToFit()

    let button3 = UIButton()
    button3.setTitle("Button 3", for: UIControlState.normal)
    button3.setTitleColor(UIColor.blue, for: UIControlState.normal)
    button3.frame.origin.y = 190
    button3.sizeToFit()
    controller = CustomButtonController(buttons: button1, button2, button3)
    self.view.addSubview(button1)
    self.view.addSubview(button2)
    self.view.addSubview(button3) 
}