[swift3] WKWebView에서 UIGesture Recognizer 사용

import UIKit

//WebKit Frameworkをインポート
import WebKit

class WebviewController: UIViewController, UIGestureRecognizerDelegate {

    //WKWebviewの宣言
    var _webkitview: WKWebView?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        //WebKitのインスタンス作成
        self._webkitview = WKWebView()

        //WebKitをviewに紐付け
        self.view = self._webkitview!

        // ジェスチャーを生成(今回はタップ・スワイプ・長押し)
        let tapGesture:UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(WebviewController.tap(_:)))
        let swipeGesture:UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: #selector(WebviewController.swipe(_:)))
        let longPressGesture:UILongPressGestureRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(WebviewController.longPress(_:)))

        // デリゲートをセット
        tapGesture.delegate = self;
        swipeGesture.delegate = self;
        longPressGesture.delegate = self;

        // WebViewに追加
        self._webkitview!.addGestureRecognizer(tapGesture)
        self._webkitview!.addGestureRecognizer(swipeGesture)
        self._webkitview!.addGestureRecognizer(longPressGesture)

        //URLを作って表示
        var url:NSURL
        url = NSURL(string:"http://******")!

        let req:NSURLRequest;

        req = NSURLRequest(url:url as URL, cachePolicy: NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData, timeoutInterval: 0)

        self._webkitview!.load(req as URLRequest)

        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func gestureRecognizer(
        _ gestureRecognizer: UIGestureRecognizer,
        shouldRecognizeSimultaneouslyWith
        otherGestureRecognizer: UIGestureRecognizer
        ) -> Bool {
        return true
    }

    func tap(_ sender: UITapGestureRecognizer){
        //タップ時の処理
        print("tap")
    }

    func swipe(_ sender: UITapGestureRecognizer){
        //スワイプ時の処理
        print("swipe")
    }

    func longPress(_ sender: UITapGestureRecognizer){
        //長押し時の処理
        print("longPress")
    }

}