在Webview iOS中注入JavaScript代码

问题描述

我创建了一个带有快速语言代码的iOS网络浏览器。并添加一个额外的按钮来在该网页上注入脚本，但是当我尝试这个时它总是崩溃：

I created a iOS web browser with swift language code. And add an extra button to inject a script on that web page, but it always crash when I try this:

webView!.evaluateJavaScript("document.body.style.background = 'red';", nil)

任何想法怎么解决这个问题？以及如何从文件中读取JavaScript代码，然后将其注入到该webview元素。

Any idea how to fix this? And how to read the JavaScript code from a file, and then inject it to that webview element.

我使用代码样式作为此示例，但使用 WKWebView ：

I use the code style as this example but with WKWebView: https://github.com/rshankras/WebViewDemo

如果你能解决这个问题，我需要一个基本的工作代码。以及如何从文件加载JavaScript的解决方案。并将该代码注入WKWebView元素。

推荐答案

这将适用于WKWebView。别忘了在类定义的顶部添加WebKit框架工作

This will work with WKWebView. Dont forget to add WebKit frame work on top on your class definition

      var webView: WKWebView!

 func loadWebViewWithCustomJavaScript {
    //Create Preferences
    let preferences = WKPreferences()
    preferences.javaScriptEnabled = true
    //Initialise javascript file with user content controller and configuration
    let configuration = WKWebViewConfiguration()
    let scriptURL =    NSBundle.mainBundle().pathForResource("Your File Name", ofType: "js")
    var scriptContent = ""
    do {
        scriptContent = try String(contentsOfFile: scriptURL!, encoding: NSUTF8StringEncoding)
    } catch{
    print("Cannot Load File")
   }
    let script = WKUserScript(source: scriptContent, injectionTime: .AtDocumentStart, forMainFrameOnly: true)
    configuration.userContentController.addUserScript(script)
    configuration.preferences = preferences
    //Create WebView instance
    webView = WKWebView(frame: CGRectMake(0,0, self.view.frame.size.width, self.view.frame.size.height), configuration: configuration)
    view.addSubview(webView)
    //Finally load the url
    let url = NSURL(string:"your URL")
    let urlRequest = NSURLRequest(URL: url!)
    webView.loadRequest(urlRequest)
  }

示例JavaScript注入代码

Sample JavaScript code for injection

 //Hides name of "background1" element on the page
 var styleTag = document.createElement("style");
 styleTag.textContent = 'div#background1, .after-post.widget-area      {display:none;}';
document.documentElement.appendChild(styleTag);

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