Trying to implement Signup with Facebook function in my App - ios

Question

I have a custom button for users to register with Facebook. However when I test it is shows that I have authorized the app, but it stays on the safari page and does not return to my app. Here is what my code looks like so far.
#IBAction func facebookButtonWasHit(sender: AnyObject) {
let permissions = [ "public_profile", "email" ]
FBSDKLoginManager().logInWithReadPermissions(permissions, fromViewController: nil, handler: { (result, error) in
if error != nil {
self.presentViewController(UIAlertController(title: "Whoops!", message: error!.localizedDescription), animated: true, completion: nil)
}
else if result.isCancelled {
self.presentViewController(UIAlertController(title: "Whoops!", message: "We couldn't access facebook! Did you hit cancel?"), animated: true, completion: nil)
}
else {
if((FBSDKAccessToken.currentAccessToken()) == nil){
FBSDKGraphRequest(graphPath: "me", parameters:["fields":"email,name"]).startWithCompletionHandler({ (connection, result, error) in
if error != nil {
self.presentViewController(UIAlertController(title: "Whoops!", message: error!.localizedDescription), animated: true, completion: nil)
} else {
if let loginResult = result as? Dictionary<String,AnyObject> {
dispatch_async(dispatch_get_main_queue(), {
if let emailID = loginResult["email"] as? String{
self.emailTextField.text = emailID
}
self.nameTextField.text = loginResult["name"] as? String
let userID = loginResult["id"] as! String
let facebookProfileUrl = "http://graph.facebook.com/\(userID)/picture?type=large"
let url = NSURL(string:facebookProfileUrl)
self.picChanged = true
self.downloadImage(url!)
})
}
}
})
}
}
})
}