Swift3 KWWebView的页面屏幕自适应

  lazy var webView:WKWebView = {
        /*
         NSString *jScript = @"var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);";
         WKUserScript *wkUScript = [[WKUserScript alloc] initWithSource:jScript injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
         WKUserContentController *wkUController = [[WKUserContentController alloc] init];
         [wkUController addUserScript:wkUScript];
         WKWebViewConfiguration *wkWebConfig = [[WKWebViewConfiguration alloc] init];
         wkWebConfig.userContentController = wkUController;
         _myWebView = [[WKWebView alloc] initWithFrame:CGRectMake(0,CGRectGetMaxY(headerView.frame)+10, M_S.width,M_S.height - CGRectGetMaxY(headerView.frame) - 40) configuration:wkWebConfig];
         */
        let js = "var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta)";
        let configuration = WKWebViewConfiguration()
        let userScript = WKUserScript(source: js, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
        let wkUController = WKUserContentController()
        wkUController.addUserScript(userScript)
        configuration.userContentController = wkUController;
        let wkView = WKWebView(frame: CGRect(x: 0.0, y: 64.0, width: swidth, height: sheight-64), configuration: configuration)
        wkView.navigationDelegate = self
        wkView.scrollView.delegate = self;
        return wkView;
    }()

　　参考:http://stackoverflow.com/questions/26295277/wkwebview-equivalent-for-uiwebviews-scalespagetofit