如何在Swift的子视图类中创建警报？ [英] How to create an alert in a subview class in Swift?

问题描述

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。

I have a view controller which contains a sub-view. And inside the sub-view class, I may need to pop out an alert when some condition is satisfied.

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内创建对父控制器的周引用吗？实现此类引用的最佳做法是什么？

As you can see from the code, I cannot call presentViewController function to show the alert because my sub view is not a controller class. Should I somehow create a week reference to the parent controller inside the sub-view? What would be the best practice to implement such reference?

推荐答案

有几种方法可以捕获 UIViewController 在你的 UIView 。

there are couple of ways how you can catch a UIViewController in your UIView.

1. 你可以将任何视图控制器作为委托来显示警报;


2. 您可以将视图控制器的参考传递给您的视图;和


3. 一般来说，您可以随时在代码中的任何位置获取 rootViewController 。

1. you can make any of your view controllers as a delegate to show an alert;
2. you can pass a view controller's reference to your view; and
3. in general you can always grab the rootViewController anywhere in your code.

当你想要解除警报时，你需要在同一个视图控制器上调用 dismissViewControllerAnimated（_：completion :) 之后。

you need to call the dismissViewControllerAnimated(_: completion:) on the same view controller when you'd like to dismiss your alert later.

因此，我会为你的案子做一个快速的解决方案：

thus, I'd do such a quick solution for your case:

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)
    }
}

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