停止任务，直到发生 AlertController 操作 Swift

Question

我试图从 present 的 completion 参数执行一个任务，这样它只会在 UIAlertController 关闭后才执行所需的功能。但是，在警报中采取操作之前调用了该函数。如何等待执行功能直到执行操作？

let alert = UIAlertController(title: "Wild Card Played", message: "Choose your suit", preferredStyle : .alert);
for suit in suits {
    alert.addAction(UIAlertAction(title: suit, style: .default, handler: crazyEightPlayed))
                  }
self.present(alert, animated: true, completion: cpuTurn) //Upon completion call the cpuTurn() function

Answer 1

当前的问题是 cpuTurn 在向用户显示警报时被调用，而不是在用户按下 "Okay" 时被调用。正如您在 documentation here 中看到的那样，self.present 方法中的完成函数是“在演示结束后[执行]。此块没有 return 值并且不带参数。您可以指定此参数为零。”为用户显示警报，第一个 UIViewController 说 "I have completed presenting the alert" 然后运行 cpuTurn 函数。

您需要将代码放入您似乎已经拥有的 UIAlertAction 的处理程序中。您应该将 cpuTurn 调用移至 crazyEightPlayed 函数（或至少从 crazyEightPlayed 调用 cpuTurn）

Answer 2

您可以尝试禁用具有交互作用的视图的子视图。我会记下那些子视图，然后只激活那些子视图。

Swift 2:

var disabledSubviews = [UIView]()

let alert = UIAlertController(title: "Title", message: "Message", preferredStyle: .Alert)
alert.addAction(UIAlertAction(title: "Ok", style: .Default, handler: { (action) in
    for subview in disabledSubviews {
        subview.userInteractionEnabled = true
    }
}))

self.presentViewController(alert, animated: true) { 
    for subview in self.view.subviews {
        if subview.userInteractionEnabled == true {
            disabledSubviews.append(subview)
            subview.userInteractionEnabled = false
        }
    }
}

Swift 3:

var disabledSubviews = [UIView]()

let alert = UIAlertController(title: "Title", message: "Message", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action) in
    for subview in disabledSubviews {
        subview.isUserInteractionEnabled = true
    }
}))
self.present(alert, animated: true) { 
    for subview in self.view.subviews {
        if subview.isUserInteractionEnabled == true {
            disabledSubviews.append(subview)
            subview.isUserInteractionEnabled = false
        }
    }
}

停止任务，直到发生 AlertController 操作 Swift

Stop tasks until AlertController action occurs Swift

xcode

ios

swift

swift3

xcode8