导航栏隐藏正确方式

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

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