加载HTML字符串内容时，字体自适应屏幕问题处理，在创建 WKWebView 时，注入相关的js：
WKWebViewConfiguration *wkWebConfig = [[WKWebViewConfiguration alloc] init];
NSString *jSString = @"var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);";
WKUserScript *script = [[WKUserScript alloc] initWithSource:jSString injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
对于图片处理，图片高度自适应,在html富文本中加入
NSString *htmls = [NSString stringWithFormat:@"<html> \n"
"<head> \n"
"<style type=\"text/css\"> \n"
"body {font-size:15px;}\n"
"</style> \n"
"</head> \n"
"<body>"
"<script type='text/javascript'>"
"window.onload = function(){\n"
"var $img = document.getElementsByTagName('img');\n"
"for(var p in $img){\n"
" $img[p].style.width = '100%%';\n"
"$img[p].style.height ='auto'\n"
"}\n"
"}"
"</script>%@"
"</body>"
"</html>",htmlString];
[self.webView loadHTMLString:htmls baseURL:nil];
