allowsBackForwardNavigationGestures = true no funciona en xcode 7.1

import UIKit import WebKit class ViewController: UIViewController, WKNavigationDelegate { var webView : WKWebView! override func loadView() { webView = WKWebView() webView.navigationDelegate = self self.view = webView } override func viewDidLoad() { super.viewDidLoad() let url = NSURL(string: "http://boooo.com") webView.loadRequest(NSURLRequest(URL: url!)) webView.allowsBackForwardNavigationGestures = true } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() } } 

Todo funciona bien pero permiteBackForwardNavigationGestures = true no funciona en xcode 7.1. No puede volver atrás y adelante en wkwebview.