iphone viewWillAppear not firing

I've read numerous posts about people having problems with viewWillAppear when you do not create your view heirarchy JUST right. My problem is I can't figure out what that means.

If I create a RootViewController and call addSubView on that controller, I would expect the added view(s) to be wired up for viewWillAppear events.

Does anyone have an example of a complex programmatic view heirarchy that successfully recieves viewWillAppear events at every level?

Apple Docs state:

Warning: If the view belonging to a view controller is added to a view hierarchy directly, the view controller will not receive this message. If you insert or add a view to the view hierarchy, and it has a view controller, you should send the associated view controller this message directly. Failing to send the view controller this message will prevent any associated animation from being displayed.

The problem is that they don't describe how to do this. What the hell does "directly" mean. How do you "indirectly" add a view.

I am fairly new to Cocoa and iPhone so it would be nice if there were useful examples from Apple besides the basic Hello World crap.

Any help is greatly appreciated...

 

answers:

(1)f you use a navigation controller and set its delegate, then the view{Will,Did}{Appear,Disappear} methods are not invoked.

You need to use the navigation controller delegate methods instead:

navigationController:willShowViewController:animated: 

navigationController:didShowViewController:animated:

(2)I've run into this same problem. Just send a viewWillAppear message to your view controller before you add it as a subview. (There is one BOOL parameter which tellsthe view controller if it's being animated to appear or not.)

[myViewController viewWillAppear:NO];

Look at RootViewController.m in the Metronome example.

(I actually found Apple's example projects great. There's a LOT more than HelloWorld ;)

转:  

http://blog.csdn.net/koupoo/article/details/6528463