Question

when we do like this

self.navigationController.toolBarHidden = NO;

question : where does navigationController come from. I take a look at UIViewController.h but I can not find that property at all

Please advice me on this. Thanks

Answer 1

Look at the UINavigationControllerItem category on UIViewController (in UINavigationControler.h):

@interface UIViewController (UINavigationControllerItem)

@property(nonatomic,readonly,retain) UINavigationItem *navigationItem; // Created on-demand so that a view controller may customize its navigation appearance.
@property(nonatomic) BOOL hidesBottomBarWhenPushed; // If YES, then when this view controller is pushed into a controller hierarchy with a bottom bar (like a tab bar), the bottom bar will slide out. Default is NO.
@property(nonatomic,readonly,retain) UINavigationController *navigationController; // If this view controller has been pushed onto a navigation controller, return it.

@end