bunnyhero dev

This is just a short note about a change I discovered between iPhone OS 2.x and 3.0. It’s not very interesting or exciting but I thought I’d record it in the off chance that it helps someone else.

When the user switches tabs on a UITabBarController in iPhone OS 2.x, the sequence of events is:

1. UIView of new tab gets added as a subview
2. UIView of old tab gets removed
3. The delegate’s tabBarController:didSelectViewController: method is called

Run the same code on iPhone OS 3.0, however, and the sequence is this:

1. UIView of new tab gets added as a subview
2. The delegate’s tabBarController:didSelectViewController: method is called
3. UIView of old tab gets removed (sometime later, I think it’s invoked via one of NSObject‘s performSelector: methods)

This is a inconsequential change for most, but it might make a difference if you are checking the UIViews’ superview variables in your tab bar controller delegate method.