how to call an AppDelegate method from RootViewController without passing a delegate?

Question

how to call an AppDelegate method from RootViewController without passing a delegate?

Just wondering whether there is a way to do this? (or do I need to create a delegate object in the RootViewController to hold a reference to the AppDelegate)

Answer 1

[[[UIApplication sharedApplication] delegate] someMethod];

奇迹般有效！

Answer 2

您可以使用以下任何方式从任何控制器访问应用程序委托：

MyDelegate* aDelegate = (MyDelegate *)[[UIApplication sharedApplication] delegate];

Answer 3

This happens so frequently, that I always add a method to MyCustomAppDelegate to do this for me (so I don't have a lot of casting in my code.

@implementation MyCustomAppDelegate ()
- (MyCustomAppDelegate *)appDelegate {
  return (MyCustomAppDelegate *)[[UIApplication sharedApplication] delegate];
}
@end

now anywhere i can call

[MyCustomAppDelgate appDelegate]