image adaption in webView

WKWebView_Image_adaption

    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        if webView.canGoBack {
            // html padding
            let javascriptString = "document.body.style.padding='0px 12px 0px 12px';   "
            webView.evaluateJavaScript(javascriptString) { (obj, error) in
                print(obj)
            }
            
            let imgJs = "function getImages(){"
                + "var objs = document.getElementsByTagName(\"img\");"
                + "var imgScr = '';"
                + "for(var i=0;i<objs.length;i++){"
                + "    imgScr = imgScr + objs[i].src + '+';"
                + "};"
                + "return imgScr;"
                + "};"
            webView.evaluateJavaScript(imgJs, completionHandler: nil)
            
            webView.evaluateJavaScript("getImages()", completionHandler: { (obj, error) in
                if let urls = obj as? String {
                    self.urls = urls.components(separatedBy: "+")
                    print(self.urls)
                    for i in 0..<self.urls.count-1 {
                        // image width
                        webView.evaluateJavaScript("document.getElementsByTagName('img')[\(i)].style.width = '100%';", completionHandler: nil)
                        
                        // click
                        // 无效?
                        let clickJS = "function registerImageClickAction(){"
                        + "    var imgs=document.getElementsByTagName('img');"
                        + "    var length=imgs.length;"
                        + "    for(var i=0;i<length;i++){"
                        + "        img=imgs[i];"
                        + "        img.onclick=function(){"
                        + "            window.location.href='image-preview:'+this.src}"
                        + "    }"
                        + "}"
                        webView.evaluateJavaScript(clickJS, completionHandler: nil)
                        webView.evaluateJavaScript("registerImageClickAction();", completionHandler: { (obj, error) in
                            print(obj?)
                        })
                    }
                    
                }
            })
            
        }
    }