Question

如果用户需要登录才能访问某项功能，但是当我按下警告self.self.performSegueWithIdentifier("tryonToLogin", sender:self)中的登录按钮时似乎无法执行任何操作时，我会尝试向用户发出提醒。

LoginViewController

@IBAction func unwindToLogin(segue:UIStoryboardSegue){

}

UIAlert

 @IBAction func goToGallery(sender: UIButton){
    if(isLoggedIn){
        performSegueWithIdentifier("ShowGallery", sender: sender)
    }else{
        showMessage("You must login to view access this feature", sender:sender)
    }
}

func showMessage(popUpMessageText : String, sender:UIButton){
    let messageTitle = "Error"

    print("prepreform segue")
    performSegueWithIdentifier("unwindToLogin", sender:sender)

    let refreshAlert = UIAlertController(title: messageTitle, message: popUpMessageText, preferredStyle: UIAlertControllerStyle.Alert)

    refreshAlert.addAction( UIAlertAction(title: "Login", style: .Default, handler: { (action: UIAlertAction!) in
        print("Handle Login redirect logic here")
        self.performSegueWithIdentifier("unwindToLogin", sender: self)
        print("after Handle Login redirect logic here")
    }))

    refreshAlert.addAction(UIAlertAction(title: "Cancel", style: .Default, handler: { (action: UIAlertAction!) in
        print("Handle Cancel logic here")
    }))


    presentViewController(refreshAlert, animated: true, completion: nil)

}

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
    print("prepare for segue called")
    self.camera = nil
}

没有错误。它被调用，好像我输入一个不存在的id我得到了没有segue与指定的标识符发现错误消息。 UIAlert是否会影响performSegueWithIdentifier()

的调用

以下帖子使用这种方法，所以我认为它应该有效。我错过了什么。

** IB截图**

修改

我已经尝试移动self.performSegueWithIdentifier("unwindToLogin", sender:self)以查看确实已显示但仍然是鼻涕工作。

Answer 1

块内的self是UIAlertController，而不是UIViewController。创建对UIViewController的弱引用，并在该对象上调用该方法。

weak var weakSelf = self

let refreshAlert = UIAlertController(title: messageTitle, message: popUpMessageText, preferredStyle: UIAlertControllerStyle.Alert)

refreshAlert.addAction( UIAlertAction(title: "Login", style: .Default, handler: { (action: UIAlertAction!) in
    print("Handle Login redirect logic here")
    dispatch_async(dispatch_get_main_queue()) {
        weakSelf?.performSegueWithIdentifier("unwindToLogin", sender:self)
    }
}))

Answer 2

看到你没有提供足够的信息，我向你展示了这个'解决方案'。

创建UIViewController的扩展，以实现设施功能以实现alertView -
我想您将代码放在“viewDidLoad”上：您必须在“viewDidAppear”上移动代码。
请检查您在 prepareForSegue

我认为这就足够了。

extension UIViewController {

    /**
     Show alert view with OK/Cancel button.

     - parameter title:       alert title
     - parameter message:     alert message
     - parameter onOk:        callback on ok button tapped
     - parameter onCancel:    callback on cancel button tapped

     - returns: alert controller
     */
    func showAlert(title title: String, message: String, onOk: (() -> ())?, onCancel: (() -> ())? = nil) -> UIAlertController {
        let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)
        let okAction = UIAlertAction(title: "Ok", style: .Default) { (alert: UIAlertAction!) -> Void in
            onOk?()
        }
       let cancelAction = UIAlertAction(title: "Cancel"), style: .Default) { (alert: UIAlertAction!) -> Void in
            onCancel?()
        }
        alertController.addAction(okAction)
        alertController.addAction(cancelAction)
        self.presentViewController(alertController, animated: true, completion: nil)
        return alertController
    }

}

class LoginViewController: UIViewController {
      override func viewDidAppear(animated: Bool) {
         super.viewDidAppear(animated) 
         let title = "Login"
         let message = messageTitle
         self.showAlert(title: title, message: message, onOk: { () -> () in
            self.performSegueWithIdentifier("unwindToLogin", sender: self)
         })  
      }
}

解开UIAlert中的segue无法正常工作

2 个答案: