viewWillAppear being called twice in iOS5

Question

I\'m running all my apps to make sure it\'s not just one app, and in every app I have, when I run on the iOS5 simulator or device, the viewWillAppear method get

Answer 1

It's the -addSubview: method.

When adding or removing view controller's view, someone must call 'View Event' methods such as -viewWillAppear:, etc. of the view controller.

Actually, it wasn't a recommended way to -addSubview:/-removeFromSuperView view controller's view by yourself before iOS 5, because it doesn't call 'View Event' methods (you can/should call it by yourself). Instead, it was recommended to use 'indirect' way to do that, such as -presentModalViewController: you use (it does call 'View Event' methods on your behalf).

On iOS 5, Apple has changed the behavior of -addSubview:/-removeFromSuperView methods to allow direct view management of view controller. So now, when you use those methods on viewController's view, 'View Event' methods will be called automatically.

So it was called twice.

See video "Implementing UIViewController Containment" on here also.