I cannot use viewDidAppear and viewDidDisappear at the same project

radarMap is a UIWebView object and exitMapButton is its close button. To access map I used hidden actions. Now I want to add fade out and fade in animations while hiding. I did fade in but not fade out. How can I add fade out animation while hiding?

func openRadarMap(){
        radarMap.hidden = false
        exitMapButton.hidden = false
        self.radarMap.alpha = 0
        self.exitMapButton.alpha = 0

    }

    override func viewDidAppear(animated: Bool) {

        if radarMap.hidden == false {
        super.viewDidAppear(animated)
        UIView.animateWithDuration(0.5, animations: {
            self.radarMap.alpha = 1.0
            self.exitMapButton.alpha = 1.0
        }) }
    }

    func exitFromMap() {
        exitMapButton.hidden = true
        radarMap.hidden = true
        self.exitMapButton.alpha = 0.0
        self.radarMap.alpha = 0.0
    }



    override func viewDidDisappear(animated: Bool) {
        super.viewDidDisappear(animated)
        UIView.animateWithDuration(0.5, animations: {
            self.radarMap.alpha = 0.0
            self.exitMapButton.alpha = 0.0
        })
    }

    @IBAction func exitMapButtonAction(sender: AnyObject) {
        exitFromMap()
    }



    @IBAction func webView(sender: UIButton) {
        getAd()
       openRadarMap()
        let URL = "http://ift.tt/1P8sF1U"
        let requestURL = NSURL(string:URL)
        let request = NSURLRequest(URL: requestURL!)
        radarMap.loadRequest(request)
        //performSegueWithIdentifier("mapView", sender: nil)
    }