navigationController和tabBarController的隐藏

self.navigationController.navigationBarHidden = YES;

//1.设置self.tabBarController.tabBar.hidden=YES;
     
self.tabBarController.tabBar.hidden=YES;
 
//2.如果在push跳转时需要隐藏tabBar，设置self.hidesBottomBarWhenPushed=YES;
 
    self.hidesBottomBarWhenPushed=YES;
    NextViewController *next=[[NextViewController alloc]init];
    [self.navigationController pushViewController:next animated:YES];
    self.hidesBottomBarWhenPushed=NO;
 
//并在push后设置self.hidesBottomBarWhenPushed=NO;
//这样back回来的时候，tabBar会恢复正常显示。