UIWindow函数在Xcode11.3中不起作用吗？

Question

我有像这样的alertcontroller控制器代码。

但我尝试显示警报，但警报没有显示给我。

对我来说有任何想法。

谢谢。

public extension UIAlertController {
    func show() {
        let win = UIWindow(frame: UIScreen.main.bounds)
        let vc = UIViewController()
        vc.view.backgroundColor = .clear
        win.rootViewController = vc
        win.windowLevel = UIWindow.Level.alert + 1
        win.makeKeyAndVisible()
        vc.present(self, animated: true, completion: nil)
    }
}


let alertController = UIAlertController(title: newTitle, message: newMessage, preferredStyle: .alert)

let submit = UIAlertAction(title: submitTitle, style: .default) { (action) in
                clickOK()
            }

alertController.addAction(submit)
if let cancelTitle = cancelTitle, !cancelTitle.isEmpty {
    let cancel = UIAlertAction(title: cancelTitle, style: .cancel) { (action) in
        if let clickCancel = clickCancel {
          clickCancel()
        }
    }
    alertController.addAction(cancel)
}

alertController.show()

Answer 1

似乎您需要保持UIWindow对象，直到您想要显示警报，这里是工作代码，只做了很小的更改

private var win: UIWindow!
extension UIAlertController {
    func show() {
        win = UIWindow(frame: UIScreen.main.bounds)
        let vc = UIViewController()
        vc.view.backgroundColor = .clear
        win.rootViewController = vc
        win.windowLevel = .alert + 1
        win.makeKeyAndVisible()
        win.rootViewController?.present(self, animated: true, completion: nil)
    }

    open override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        win = nil
    }
}

使用

使用方法与您之前使用的方法相同

let alertController = UIAlertController(title: newTitle, message: newMessage, preferredStyle: .alert)

let submit = UIAlertAction(title: submitTitle, style: .default) { (action) in
                clickOK()
            }

alertController.addAction(submit)
if let cancelTitle = cancelTitle, !cancelTitle.isEmpty {
    let cancel = UIAlertAction(title: cancelTitle, style: .cancel) { (action) in
        if let clickCancel = clickCancel {
          clickCancel()
        }
    }
    alertController.addAction(cancel)
}

alertController.show()

Answer 2

你也可以使用这个swift 5.0扩展

  public extension UIAlertController {

    func showAlert() {
    let window = UIWindow(frame: UIScreen.main.bounds)
    let vc = UIViewController()
    vc.view.backgroundColor = .clear
    window.rootViewController = vc
    window.windowLevel = UIWindow.Level.alert + 1  
    window.makeKeyAndVisible()    
    vc.present(self, animated: true, completion: nil)
}
}

使用标题和消息设置警报控制器，并像这样调用

 alertObject.showAlert()