获取UIWebView的内容高度

#pragma mark - UIWebview delegete

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];
    CGRect frame = webView.frame;
    webView.frame = CGRectMake(frame.origin.x, frame.origin.y, frame.size.width, height);
}