链接 UIAlertAction 以打开另一个 ViewController

Question

基本上我有一个 uialertaction 需要在按下时显示另一个视图控制器。起初我是这样做的，但现在即使我没有收到错误代码，应该打开的视图控制器也只是一个黑页。

            if((user) != nil) {

                let alert = UIAlertController(title: "Succesfull", message: "Logged In", preferredStyle: UIAlertControllerStyle.Alert)

                    self.presentViewController(alert, animated: true, completion: nil)

                        let delay = 2.0 * Double(NSEC_PER_SEC)

                            let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
                            dispatch_after(time, dispatch_get_main_queue(), {

                            alert.dismissViewControllerAnimated(true, completion: { () -> Void in

                                let logInViewController = BoardViewController()

                                    self.presentViewController(logInViewController, animated: true, completion: nil)

实际上几天前我遇到了这样的问题，但我无法正确理解答案。所以谁能解释我为什么会发生并且没有给出任何错误

Answer 1

您的 AlertController 没有任何操作。您只是在显示 AlertController 2 秒后呈现 logInViewController。

您可以像这样向 AlertController 添加操作，而不是 dispatch_after；

if(user != nil) {
      let alert = UIAlertController(title: "Succesful", message: "Logged In", preferredStyle: UIAlertControllerStyle.Alert)
      let action = UIAlertAction(title: "OK", style: .Cancel, handler: { // Also action dismisses AlertController when pressed.
            action in

              let logInViewController = BoardViewController()
              self.presentViewController(logInViewController, animated: true, completion: nil) // When press "OK" button, present logInViewController

                }
        )
      alert.addAction(callAction)// add action to alert
      self.presentViewController(alert, animated: true, completion: nil)// show AlertController
}

如果你从 BoardViewController 得到空白页，那么你的 BoardViewController 类可能有问题。