Question

我有一个包含子视图的视图控制器。在子视图类中，我可能需要在满足某些条件时弹出警报。

class GameViewController: UIViewController {
    @IBOutlet var gameBoardUIView: GameBoardUIView
    ...
}

class GameBoardUIView: UIView {
    ...
    func move() {
        if !gameBoard.checkNextMoveExist() {
            var alert = UIAlertController(title: "Game Over", message: nil, preferredStyle: UIAlertControllerStyle.Alert)
            alert.addAction(UIAlertAction(title: "Take Me Back", style: UIAlertActionStyle.Cancel, handler: {(action: UIAlertAction!) in
                println("Taking user back to the game without restarting")
            }))
            alert.addAction(UIAlertAction(title: "New Game", style: UIAlertActionStyle.Destructive, handler: {(action: UIAlertAction!) in
                println("Starting a new game")
                self.restartGame()
            }))
            // This is where the question is
            // self.presentViewController(alert, animated: true, completion: nil)
        }
    }
}

从代码中可以看出，我无法调用presentViewController函数来显示警报，因为我的子视图不是控制器类。我应该以某种方式在子视图中创建对父控制器的周引用吗？实施此类参考的最佳做法是什么？

Answer 1

有几种方法可以捕捉UIViewController中的UIView。

您可以将任何视图控制器设为委托以显示警报;
您可以将视图控制器的参考传递给您的视图;和
一般情况下，您始终可以在代码中的任意位置抓取rootViewController。

如果您希望稍后解除警报，则需要在同一个视图控制器上调用dismissViewControllerAnimated(_: completion:)。

因此，我会为您的案例做一个快速解决方案：

func move() {
    if !gameBoard.checkNextMoveExist() {

        let rootViewController: UIViewController = UIApplication.sharedApplication().windows[0].rootViewController

        var alert = UIAlertController(title: "Game Over", message: nil, preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "Take Me Back", style: UIAlertActionStyle.Cancel, handler: {(action: UIAlertAction!) in
            rootViewController.dismissViewControllerAnimated(true, completion: nil)
            println("Taking user back to the game without restarting")
        }))
        alert.addAction(UIAlertAction(title: "New Game", style: UIAlertActionStyle.Destructive, handler: {(action: UIAlertAction!) in
            rootViewController.dismissViewControllerAnimated(true, completion: nil)
            println("Starting a new game")
            self.restartGame()
        }))
        rootViewController.presentViewController(alert, animated: true, completion: nil)
    }
}

Answer 2

快捷键4

只需在根视图控制器的UIApplication窗口中显示警报：

let title = "Some title"
let message = "body message"

let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
let action = UIAlertAction(title: "Aceptar", style: .cancel, handler: nil)

alert.addAction(action)

UIApplication.shared.keyWindow?.rootViewController?.present(alert, animated: true, completion: nil)

如何在Swift的子视图类中创建警报？

2 个答案: