iOS WebView加载Html字符串并适应内容高度

最后使用的是UIWebView，解决了两个问题
1：开始使用的WKWebView，发现WKWebView加载的html字符串文字要比正常的小很多，找了几个办法都没有解决，因此只能换成了UIWebView
2：换了后这次文字倒是正常了，但是图片又不能完整显示在WebView里，后来找到JS方法在WebView加载完后调用，才解决
这里贴一下主要代码

- (void)webViewDidFinishLoad:(UIWebView *)webView {
    NSString *js=@"var script = document.createElement('script');"
    "script.type = 'text/javascript';"
    "script.text = \"function ResizeImages() { "
    "var myimg,oldwidth;"
    "var maxwidth = %f;"
    "for(i=0;i <document.images.length;i++){"
    "myimg = document.images[i];"
    "if(myimg.width > maxwidth){"
    "oldwidth = myimg.width;"
    "myimg.width = %f;"
    "}"
    "}"
    "}\";"
    "document.getElementsByTagName('head')[0].appendChild(script);";
    js = [NSString stringWithFormat:js,[UIScreen mainScreen].bounds.size.width,[UIScreen mainScreen].bounds.size.width-15];
    [webView stringByEvaluatingJavaScriptFromString:js];
    [webView stringByEvaluatingJavaScriptFromString:@"ResizeImages();"];

    NSInteger width = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.scrollWidth"] integerValue];
    CGFloat bili = width/ScreenWIDTH;
    NSInteger height = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.scrollHeight"] integerValue];
    [_PolicyWebView mas_updateConstraints:^(MASConstraintMaker *make) {
        make.height.mas_equalTo(height/bili);//更新高度
    }];
}