viewWillAppear method not getting called in iOS 4.2
I'm using Xcode 4.2. I set the deployment target as 4.2. I created an app with the view hierarchy as UIViewController > UITabBarController > UINavigationController > UIViewController.It is working fine with iOS 5. But for iOS 4.2, the viewWillAppear  method is not getting called. what would be the reason for this? 
viewWillAppear method not getting called in iOS 4.2
===

I'm using Xcode 4.2. I set the deployment target as 4.2. I created an app with the view hierarchy as UIViewController > UITabBarController > UINavigationController > UIViewController.It is working fine with iOS 5. But for iOS 4.2, the viewWillAppear  method is not getting called. what would be the reason for this? 