在webView加载完毕之后，运行下面的JS代码禁止WKWebView放大缩小
//加载完毕
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
NSString *injectionJSString = @"var script = document.createElement('meta');"
"script.name = 'viewport';"
"script.content="width=device-width, user-scalable=no";"
"document.getElementsByTagName('head')[0].appendChild(script);";
[webView evaluateJavaScript:injectionJSString completionHandler:nil];
}
