iOS iOS7 20px 处理

- (void)viewWillAppear:(BOOL)animated
{
    // View defaults to full size.  If you want to customize the view‘s size, or its subviews (e.g. webView),
    // you can do so here.

    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7 && isViewWillAppear == FALSE) {
        CGRect viewBounds = [self.webView bounds];
        viewBounds.origin.y = 20;
        viewBounds.size.height = viewBounds.size.height - 20;
        self.webView.frame = viewBounds;
        NSLog(@"m2 isViewWillAppear == FALSE");
        isViewWillAppear = TRUE;
    }

    [super viewWillAppear:animated];
}

MainViewController.m 中的   - (void)viewWillAppear:(BOOL)animated  添加以上的代码；