Question

我的根viewController包含另一个类的变量和一个显示该类视图的按钮：

class ViewController: UIViewController {

    var myBoxView = BoxView()

    override func viewDidLoad() {
        let btn = UIButton()
        btn.backgroundColor = UIColor.green
        btn.addTarget(self, action: #selector(showBoxView), for: .touchUpInside)
        view.addSubview(btn)
        btn.translatesAutoresizingMaskIntoConstraints = false
        view.addConstraint(NSLayoutConstraint(item: btn, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1, constant: 0))
        view.addConstraint(NSLayoutConstraint(item: btn, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1.5, constant: 0))
    }

}

extension ViewController {

    @objc func showBoxView(_ sender: UITapGestureRecognizer?) {
//      let myBoxView = BoxView()
        myBoxView.showView()
    }

}

另一个类符合NSObject并具有另一个按钮来关闭其视图：

class BoxView: NSObject {

    let boxView = UIView(frame: CGRect(x: 50, y: 200, width: 300, height: 300))
    let closeBtn = UIButton()

    func showView() {
        if let window = UIApplication.shared.keyWindow {
            closeBtn.addTarget(self, action: #selector(closeBoxView), for: .touchUpInside)
            closeBtn.backgroundColor = UIColor.blue
            closeBtn.translatesAutoresizingMaskIntoConstraints = false
            boxView.addSubview(closeBtn)
            boxView.addConstraint(NSLayoutConstraint(item: boxView, attribute: .centerX, relatedBy: .equal, toItem: closeBtn, attribute: .centerX, multiplier: 1, constant: 0))
            boxView.addConstraint(NSLayoutConstraint(item: boxView, attribute: .centerY, relatedBy: .equal, toItem: closeBtn, attribute: .centerY, multiplier: 1, constant: 0))

            boxView.backgroundColor = UIColor.red
            window.addSubview(boxView)
            boxView.alpha = 1
        }
    }
}

extension BoxView {

    @objc func closeBoxView(_ sender: UITapGestureRecognizer) {
        UIView.animate(withDuration: 0.3) {
            self.boxView.alpha = 0
            self.boxView.removeFromSuperview()
        }
    }

}

代码已简化。

一切正常，直到 ... （即，当一个人按下根按钮时，将触发选择器（showBoxView）并显示BoxView。然后，一个人按下关闭按钮（closeBoxView将被激发，然后淡出。然后恢复正常操作。）

当我不使用全局变量（myBoxView）并创建新实例时，该类的“关闭”按钮的选择器（closeBoxView）将不会触发。即使显示了boxView。

（即，我将let myBoxView = BoxView()插入“ showBoxView”方法的顶部）

为什么不使用选择器（closeBoxView）而不使用其实例（从根VC）呢？

PS。我通过添加AppDelegate“ didFinishLaunchingWithOptions”，以编程方式完成了此操作：

window = UIWindow(frame: UIScreen.main.bounds)
window?.makeKeyAndVisible()
window?.rootViewController = ViewController()

没有全局变量就不会触发关闭按钮选择器

0 个答案: