ScrollView下移 UIWebView 顶部出现空白条

方法1:viewDidLoad 中添加

self.automaticallyAdjustsScrollViewInsets=NO;//自动滚动调整，默认为YES

方法2:重写viewWillLayoutSubviews

-(void)viewWillLayoutSubviews {
       [superviewWillLayoutSubviews];
        _webView.scrollView.contentInset=UIEdgeInsetsZero;
}