在运行时更改用户代理

Question

我试图在我的应用程序上添加移动，桌面版本的网站功能。但问题是User Agent只在webView加载之前立即改变。在我的应用程序中，我添加到按钮一Mobile和第二Desktop版本的网站。UIWebView接User Agent刚开始。谁能告诉我有没有办法改变User Agent在运行时。由于

 var defaultUserAgent = String()
    @IBOutlet weak var webView: UIWebView!
    @IBOutlet weak var activityIndicator: UIActivityIndicatorView!
    override func viewDidLoad() {
        super.viewDidLoad()
        let url = NSURL(string: "https://www.youtube.com")
        let request = NSURLRequest(URL: url!)
        activityIndicator.hidesWhenStopped = true
        activityIndicator.startAnimating()
        webView.loadRequest(request)
    }
    @IBAction func mobile(sender: AnyObject) {
        NSUserDefaults.standardUserDefaults().registerDefaults(["UserAgent": defaultUserAgent])
        print(defaultUserAgent)
        let url = NSURL(string: "https://www.youtube.com")
        let request = NSURLRequest(URL: url!)
        activityIndicator.hidesWhenStopped = true
        activityIndicator.startAnimating()
        webView.loadRequest(request)
    }
    @IBAction func desktop(sender: AnyObject) {
        NSUserDefaults.standardUserDefaults().registerDefaults(["UserAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.109 Safari/537.36"])
        let url = NSURL(string: "https://www.youtube.com")
        let request = NSURLRequest(URL: url!)
        activityIndicator.hidesWhenStopped = true
        activityIndicator.startAnimating()
        webView.loadRequest(request)
    }
    func webViewDidFinishLoad(webView: UIWebView) {
        activityIndicator.stopAnimating()
        print(webView.stringByEvaluatingJavaScriptFromString("navigator.userAgent"))
        defaultUserAgent = webView.stringByEvaluatingJavaScriptFromString("navigator.userAgent")!
    }

Answer 1

我建议你使用WkWebView而不是UIWebView，因为它相对更强大

iOS 9的WkWebView有一个直接的API

 if #available(iOS 9, *) {
            webViewObj.customUserAgent = "customUserAgentValue"
 }