If you want to hide statusbar or tabbar from a view in a navigation controller (to display it on full screen), set
[self setWantsFullScreenLayout:YES], and that view will be presented in fullscreen mode. (e.g like in the Photos app)
To hide the statusbar or tabbar, use
viewController.hidesBottomBarWhenPushed = YES; before invoking
To have transculent-black navigation-/statusbar, use UIBarStyleBlack and set the translucent property to YES, and set tintColor to clearColor.
Source: Stackoverflow.com, iPhoneDevSDK
For stunning animations and effects, sometimes it is useful to capture the contents of the view into an image before starting the animation, or simply just save the content to an image file.
There is a quite easy way to do this on icodeblog.
If you need a calendar in your iphone app, then before starting to write your own version, try the MIT licensed Kal:
(the Holiday example includes a JSON parser)
Screenshot of the provided demo: