ios webView与js交互与类似回调的实现（swift）

直接代码，首先加载一个webView：

webView = UIWebView.init(frame: CGRect(x: 0, y: 0, width: self.view.frame.size.width, height: self.view.frame.size.height))
webView.delegate = self
webView.loadRequest(NSURLRequest(URL: NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("File", ofType: "html")!)))//本地文件测试
webView.scrollView.delegate = self
webView.scrollView.tag = 1
view.addSubview(webView)

实现方法：

func webViewDidStartLoad(webView: UIWebView) {
//        print("开始加载")
//        webView.stringByEvaluatingJavaScriptFromString("        document.write(Date());")//与js的交互通过这个方法可以在网页中相当于加入一段js代码
//    webView.stringByEvaluatingJavaScriptFromString("document.getElementById('demo').innerHTML = '段落已修改'")
}
//
func webView(webView: UIWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType) -> Bool {
if navigationType == .LinkClicked {
print("LinkClicked")

//            let uid = webView.stringByEvaluatingJavaScriptFromString("method();")
//            print("uid = \(uid!)")

//            if request.URL?.absoluteString == "http://www.baidu.com/"  {
//                let secView = WebViewController()
//                secView.webView.loadRequest(request)
//                self.navigationController?.pushViewController(secView, animated: true)
//            }
//            if request.URL?.absoluteString == "http://www.google.com/"  {
//                let secView = WebViewController()
//                secView.webView.loadRequest(request)
//                self.navigationController?.pushViewController(secView, animated: true)
//            }
return false
}
if navigationType == .BackForward {

}
if navigationType == .Other {

}
if navigationType == .FormSubmitted {
print("FormSubmitted")

}
return true
}

func webView(webView: UIWebView, didFailLoadWithError error: NSError?) {
if (error != nil) {
kError = error
}

}

func webViewDidFinishLoad(webView: UIWebView) {
//        print("jiazaijieshu")
//        let high = webView.stringByEvaluatingJavaScriptFromString("document.body.scrollHeight;")//此处运行js代码获取页面高度
//        print(high!)
let jsContext = webView.valueForKeyPath("documentView.webView.mainFrame.javaScriptContext")//获取当前js运行环境
let webBack: @convention(block) String -> () = { input in
print(input)
//            return mutableString as String

}//设置回调方法  （姑且这么称呼）
//unsafeBitCast为类型转换将type @convention(block) Swift.String -> ()转换为AnyObject，且不会对这个操作进行检查，使用unsafeBitCast要<strong>确保两边类型正确</strong>，应该使用更安全的方法，目前没找到
jsContext!.setObject(unsafeBitCast(webBack, AnyObject.self), forKeyedSubscript: "simplifyString")//在上下文中加入回调
}

func scrollViewDidScroll(scrollView: UIScrollView) {
//        if scrollView == webView.scrollView {
//            let y = webView.stringByEvaluatingJavaScriptFromString("window.pageYOffset")
//            print(y)
//        }

}

上面回调的使用是在web的代码中，
 <p><a href="http://www.baidu.com/"
id="BaiDu"
onclick="theFunc(this)" >去百度</a>  
是一个指向万维网上的页面的链接。</p>

<script>
function theFunc(obj) {
        webBack(obj.id)
    }
</script>