Swift:弹出窗口关闭回调

问题描述：

我的故事板中有两个 UIViewConrollers:MainViewController 和 SecondViewController.当用户点击一个名为 Show Popover 的按钮时，我将把 SecondViewController 显示为一个弹出框:

There are two UIViewConrollers in my Storyboard: MainViewController and SecondViewController. I'm going to show SecondViewController as a popover when user taps a button called Show Popover:

//MainViewController
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
{

    if segue.identifier == "GoToSecondViewControllerSegue"
    {
        var vc = segue.destinationViewController as! SecondViewController
        var controller = vc.popoverPresentationController

        if controller != nil
        {
            controller?.delegate = self
            vc.inputTextDelegate = "I'm a popover!"
        }
    }
}

func popoverPresentationControllerDidDismissPopover(popoverPresentationController: UIPopoverPresentationController) {
     println("done")
}

func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle
{
    return .None
}

//SecondViewController
@IBAction func dismissPopover(sender: UIButton) {
     dismissViewControllerAnimated(true, completion: nil)
     //This dismisses the popover but does not notify the MainViewConroller
}

segue 的锚点连接到一个按钮上:

The anchor of segue is connected to a button:

现在我有两个问题:

当我点击弹出框内的取消按钮时，它会关闭弹出框，但不会触发 MainViewController

如何将数据从 SecondViewController 传递到 MainViewController，例如 UITextView 的文本值.

How can I pass data from the SecondViewController to the MainViewController, text value of a UITextView for example.

答

协议和委托是解决此类问题的方法.就我而言，我定义了一个协议并使 MainViewController 符合该协议.

Protocols and delegations are solution to such problems. In my case I defined a protocol and conformed the MainViewController to the protocol.

//SecondViewController
protocol MyDelegate{
    func DoSomething(text:String)
}

class SecondViewController: UIViewController {

 var delegate:GetTextDelegate?

 var inputTextDelegate:String = ""

 override func viewDidLoad() {
    newText.text = inputTextDelegate
 }

 @IBAction func dismissPopover(sender: UIButton) {
        dismissViewControllerAnimated(true, completion: nil)
       //This dismisses the popover but does not notify the  MainViewConroller
 }
 @IBAction func doneButtonAction(sender: UIButton) {
    if let delegate = self.delegate {
        delegate.DoSomething(newText.text)
        self.dismissViewControllerAnimated(true, completion: nil)
    }
 }
}

class MainViewController: UIViewController, UIPopoverPresentationControllerDelegate, MyDelegate {


    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
    {

        if segue.identifier == "GoToSecondViewControllerSegue"
        {
            var vc = segue.destinationViewController as! SecondViewController
            vc.delegate = self
            vc.inputTextDelegate = "I'm a popover!"
        }
    }

    func popoverPresentationControllerDidDismissPopover(popoverPresentationController: UIPopoverPresentationController) {
        //...
    }

 func DoSomething(text: String) {
     //Do whatever you want
     println(text)
 }

}

Swift:弹出窗口关闭回调

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