如何创建 UIActionSheet 动作? [英] How to create UIActionSheet actions?

问题描述

我知道我必须设置委托(我这样做是这样的:class ShiftOverview: UITableViewController, UIActionSheetDelegate {...)但是当我点击按钮时仍然没有响应.

I know I have to set the delegate (I did so like this: class ShiftOverview: UITableViewController, UIActionSheetDelegate {...) but I'm still getting no response when I tap the buttons.

看起来您也不能使用 UIAlertController 在函数内设置委托...

It doesn't look like you can set the delegate within the function with UIAlertController either...

 @IBAction func takeShift(sender: AnyObject) {

    let myActionSheet = UIAlertController (title: "Confirm", message: "Test message", preferredStyle: UIAlertControllerStyle.ActionSheet)

    let actionOne = UIAlertAction (title: "Take Shift", style: .Default, handler: nil)
    let actionTwo = UIAlertAction (title: "View ESA", style: .Default, handler: nil)

    let actionCancel = UIAlertAction (title: "Cancel", style: .Cancel, handler: nil)

    myActionSheet.addAction(actionOne)
    myActionSheet.addAction(actionTwo)
    myActionSheet.addAction(actionCancel)

    self.presentViewController(myActionSheet, animated: true, completion: nil)
}

func actionSheet (myActionSheet: UIActionSheet, clickedButtonAtIndex buttonIndex: Int)
{
    switch buttonIndex {

    case 0:
        println ("test0")
        break
    case 1:
        println ("test1")
        break
    case 2:
        println ("test2")
        break

    default:
        println("nope")

    }
}

推荐答案

在 iOS 8 之前，UIAlertViews 和 UIActionSheets 是单独的控件.然而，在 iOS 8 中，一个新类 UIAlertController 将这两个控件合并到一个易于使用的类中.

Prior to iOS 8, UIAlertViews and UIActionSheets were separate controls. In iOS 8 however, a new class, UIAlertController, combines both these controls into a single, easy to use class.

与过去使用这些控件的委托模式不同，您现在传递一个要调用的闭包.handler 等于 nil 的地方就是你放置代码的地方.

Rather than using the delegation pattern like these controls used to, you now pass a closure to be called. The places where you have handler equal to nil is where you put your code.

这可能是添加的，因为 Swift 将闭包视为一等公民，而 Objective C 没有那么多(使用块).

This is likely added because Swift treats closures as first-class citizens, while Objective C did not as much (with blocks).

应该是:

@IBAction func takeShift(sender: AnyObject) {

    let myActionSheet = UIAlertController (title: "Confirm", message: "Test message", preferredStyle: UIAlertControllerStyle.ActionSheet)

    let actionOne = UIAlertAction (title: "Take Shift", style: .Default, handler: { (action) in
        println("test0")
    })
    let actionTwo = UIAlertAction (title: "View ESA", style: .Default, handler: { (action) in
        println("test1")
    })

    let actionCancel = UIAlertAction (title: "Cancel", style: .Cancel, handler: { (action) in
        println("test2")
    })

    myActionSheet.addAction(actionOne)
    myActionSheet.addAction(actionTwo)
    myActionSheet.addAction(actionCancel)

    self.presentViewController(myActionSheet, animated: true, completion: nil)
}

在 NSHipster 关于 UIAlertControllers 的文章 或其 文档.

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