方式 隐藏导航栏

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
if ([viewController isKindOfClass:NSClassFromString(@"PUUIImageViewController")]) {
[navigationController setNavigationBarHidden:YES animated:YES];
}
if ([viewController isKindOfClass:NSClassFromString(@"PUUIMomentsGridViewController")]) {
[navigationController setNavigationBarHidden:NO animated:YES];
}

}