当点击外部的UIAlertController时，如何排除UIAlertController？

Question

当点击外部的UIAlertController时，如何排除UIAlertController？

我可以添加一个UIAlertAction of style UIAlertActionStyleCancel来取消UIAlertController。

但是我想添加一个函数，当用户点击UIAlertController外部时，UIAlertController就会关闭它。怎么做？谢谢。

Answer 1

添加一个带有样式UIAlertActionStyleCancel的单独的取消操作。这样，当用户点击外部时，您将得到回调。

Obj-c

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Alert Title" message:@"A Message" preferredStyle:UIAlertControllerStyleActionSheet];
[alertController addAction:[UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
 // Called when user taps outside
}]];

Swift 5.0

let alertController = UIAlertController(title: "Alert Title", message: "A Message", preferredStyle: .actionSheet)             
alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { 
    action in
         // Called when user taps outside
}))

Answer 2

如果您的目标设备的iOS > 9.3，并且使用Swift和preferredStyle is Alert，您可以使用以下代码片段：

func showAlertBtnClicked(sender: UIButton) {
    let alert = UIAlertController(title: "This is title", message: "This is message", preferredStyle: .Alert)
    self.presentViewController(alert, animated: true, completion:{
        alert.view.superview?.userInteractionEnabled = true
        alert.view.superview?.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.alertControllerBackgroundTapped)))
    })
}

func alertControllerBackgroundTapped()
{
    self.dismissViewControllerAnimated(true, completion: nil)
}

与迅捷3：

func showAlertBtnClicked(sender: UIButton) {
    let alert = UIAlertController(title: "This is title", message: "This is message", preferredStyle: .alert)
    self.present(alert, animated: true) {
        alert.view.superview?.isUserInteractionEnabled = true
        alert.view.superview?.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.alertControllerBackgroundTapped)))
    }
}

func alertControllerBackgroundTapped()
{
    self.dismiss(animated: true, completion: nil)
}

Answer 3

Swift，Xcode 9

取消AlertController按钮

向您的alertController提供UIAlertAction的样式为.cancel的操作

let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
alertController.addAction(cancelAction)

使用这种方法，当用户点击“取消操作”按钮，以及在alertController之外时，alertController将被取消。

如果您不希望用户在alertController之外修改后拒绝使用alertController，那么在完成当前方法的闭包过程中，禁用alertController的第一个子视图的用户交互。

self.present(alertController, animated: true) {
     alertController.view.superview?.subviews[0].isUserInteractionEnabled = false
    }

在Controller视图之外的触摸时取消AlertController

如果您不希望在控制器视图中取消按钮，并且希望在用户在控制器视图之外触摸时关闭控制器，请这样做。

self.present(alertController, animated: true) {
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(self.dismissAlertController))
        alertController.view.superview?.subviews[0].addGestureRecognizer(tapGesture)
}

@objc func dismissAlertController(){
    self.dismiss(animated: true, completion: nil)
}