AlertController is not in the window hierarchy

Question

I\'ve just created a Single View Application project with ViewController class. I would like to show a UIAlertController from a function which is located inside my own class

Answer 1

Write the following 3 lines, all we need to do is this.

Swift 3.0

private func presentViewController(alert: UIAlertController, animated flag: Bool, completion: (() -> Void)?) -> Void {
     UIApplication.shared.keyWindow?.rootViewController?.present(alert, animated: flag, completion: completion)
  }

Swift 2.0

  private func presentViewController(alert: UIAlertController, animated flag: Bool, completion: (() -> Void)?) -> Void {
     UIApplication.sharedApplication().keyWindow?.rootViewController?.presentViewController(alert, animated: flag, completion: completion)
  }