1.
-(void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
[self.navigationController setNavigationBarHidden:NO animated:NO];
}
-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
[self.navigationController setNavigationBarHidden:YES animated:YES];
}
2.在需要隐藏导航栏的页面不要隐藏,把导航栏以及导航栏下的黑线都设置成透明的图片即可,效果是一样的。