【iOS11】适配问题

• 在iOS11运行视图[view class]向下20px问题解决

if (@available(iOS 11.0, *)) {
        scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
    } else {
        // Fallback on earlier versions
        self.automaticallyAdjustsScrollViewInsets = NO;
    }