ios9 到 11遇到的坑

1. ios11 tabBarController 去除 tabBar 不能再 viewDidLoad 而是 viewDidAppear

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    // ios11 删除系统自动生成的UITabBarButton
    for (UIView *child in self.tabBar.subviews) {
        if ([child isKindOfClass:[UIControl class]]) {
            [child removeFromSuperview];
        }
    }
}