Swift 写一个简单的浏览器

import UIKitclass ViewController: UIViewController,UIWebViewDelegate,UITextFieldDelegate{    @IBOutlet weak var web1: UIWebView!    @IBOutlet weak var textField1: UITextField!    @IBOutlet weak var loding: UIActivityIndicatorView!    override func viewDidLoad() {        super.viewDidLoad()        // Do any additional setup after loading the view, typically from a nib.    }        func textFieldShouldReturn(textField: UITextField) -> Bool {            //载入输入的网址请求            loadurl(textField.text, web: web1)            //接触第一反应，键盘消失            textField.resignFirstResponder()            return true    }            //载入网页请求    func loadurl (url: String, web: UIWebView) {        let aurl = NSURL (string:"http://" + (url))                let urlrq = NSURLRequest (URL: aurl!)                web.loadRequest(urlrq)    }    //网页开始载入动画    func webViewDidStartLoad(webView: UIWebView) {        loding.startAnimating()        //左上角齿轮出现        UIApplication.sharedApplication().networkActivityIndicatorVisible = true    }    //网页载入结束动画    func webViewDidFinishLoad(webView: UIWebView) {        loding.stopAnimating()        //左上角齿轮消失        UIApplication.sharedApplication().networkActivityIndicatorVisible = false    }    override func didReceiveMemoryWarning() {        super.didReceiveMemoryWarning()        // Dispose of any resources that can be recreated.    }}