如何调用我的自定义警报控制器function以显示在其他视图控制器中？

我已经编写了我的自定义警报视图控制器。但是，我在从其他视图控制器调用我的警报控制器时出错。它显示了我在下面描述的错误。

控制台出错

2015-06-15 10:21:50.610 automobile[4197:62165] Warning: Attempt to present  on  whose view is not in the window hierarchy! 

这是我的LoadingAlertViewController

 import UIKit class LoadingAlertViewController: UIAlertController { var loadingAlertController : UIAlertController! override func viewDidLoad() { super.viewDidLoad() } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } func displayLoadingAlert() -> UIAlertController { var controllerToPresent = viewController if controllerToPresent == nil { controllerToPresent = self } //create an alert controller loadingAlertController = UIAlertController(title: "Loading...", message: "We are receiving data from network.Please Wait.", preferredStyle: .Alert) let indicator = UIActivityIndicatorView() indicator.color = UIColor.redColor() indicator.setTranslatesAutoresizingMaskIntoConstraints(false) loadingAlertController.view.addSubview(indicator) let views = ["pending" : loadingAlertController.view, "indicator" : indicator] var constraints = NSLayoutConstraint.constraintsWithVisualFormat("V:[indicator]-(7)-|", options: nil, metrics: nil, views: views) constraints += NSLayoutConstraint.constraintsWithVisualFormat("H:|[indicator]|", options: nil, metrics: nil, views: views) loadingAlertController.view.addConstraints(constraints) indicator.userInteractionEnabled = false indicator.startAnimating() controllerToPresent!.presentViewController(loadingAlertController, animated: true, completion: nil) return loadingAlertController } func dismissLoadingAlert() -> UIAlertController { loadingAlertController.dismissViewControllerAnimated(true, completion: nil) return loadingAlertController } } 

然后我在我的另一个视图控制器上将这个LoadingAlertViewController ，我想在每次向API请求时显示它。

这是我的ViewController 。

 import UIKit class ViewController : UIViewControler{ var loadingAlertController : LoadingAlertController! var api = MyAPI() override func viewDidLoad() { loadingAlertController = LoadingAlertViewController() api.getResults() showAlert(true) } func showAlert(alert : Bool){ if alert{ loadingAlertController.displayLoadingAlert(self) }else{ loadingAlertController.dismissLoadingAlert() } } 

任何帮助？请？如果有办法，如何从另一个视图控制器调用它。谢谢

Answer 1

像这样改变你的方法：

 func displayLoadingAlert(viewController: UIViewController?) -> UIAlertController { var controllerToPresent = viewController if controllerToPresent == nil { controllerToPresent = self } // Most of your code controllerToPresent.presentViewController(loadingAlertController, animated: true, completion: nil) return loadingAlertController } 

然后，当您拨打警报时：

 loadingAlertController.displayLoadingAlert(self) 

或者：将方法displayLoadingAlert重命名为loadingAlert

删除行：

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

然后在showAlert（）方法内部调用

 let loadingAlertController = loadingAlertController.loadingAlert() self.presentViewController(loadingAlertController, animated: true, completion: nil) 

Answer 2

我看到你作为子类，但在UIAlertController文档中写道：

UIAlertController类旨在按原样使用，不支持子类化。 此类的视图层次结构是私有的，不得修改。

我建议你不要反对它。 如果你需要一些非常自定义的东西来使用UIViewController并显示自定义行为。