iOS 隐藏NavigationBar的方法

使用下面方法：

- (void)viewWillAppear:(BOOL)animated {
	[super viewWillAppear:animated];
	
	[self.navigationController setNavigationBarHidden:YES];
}

退出该控制器时还原：

- (void)viewWillDisappear:(BOOL)animated {
	[super viewWillDisappear:animated];
	
	[self.navigationController setNavigationBarHidden:NO];
}

-- end