Swift Firebase Facebook login dialog box pop up 2 times - swift

Question

I have a facebook login which using firebase to authenticate the process.
However, after I input my login detail and press confirm. It will back to the login page and pop up the facebook login page again. Then I press confirm again. It will display "User Cancel Login".
I am not sure why does it happen 2 times also when i click the confirm button it will display "User Cancel Login"
func loginButton(FbLoginBtn: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!) {
let FbloginManager = FBSDKLoginManager()
FbloginManager.logInWithReadPermissions(["email","public_profile", "user_location", "user_hometown","user_friends"],fromViewController: self, handler: { (result, error) in
if let error = error {
print(error.localizedDescription)
return
}else if(result.isCancelled) {
print("User Cancel Login")
}else{
let credential = FIRFacebookAuthProvider.credentialWithAccessToken(FBSDKAccessToken.currentAccessToken().tokenString)
print("User\(self.user?.displayName) login successful")
AppState.instance.signedIn = true
if AppState.instance.signedIn == false{
self.firebaseLogin(credential)
//self.createFirebaseUser()
self.performSegueWithIdentifier(SEGUE_LOGIN, sender: nil)
}
}
})
}

Answer 1

For me this code work :
#IBAction func btnFBLoginPressed(sender: AnyObject) {
self.comeFromFB = true
let fbLoginManager : FBSDKLoginManager = FBSDKLoginManager()
var id:String = ""
var urlPhoto:String = ""
fbLoginManager.logInWithReadPermissions(["email"], fromViewController: self){ (result, error) -> Void in
if let error = error
{
print(error)
return
}
else
{
let fbloginresult : FBSDKLoginManagerLoginResult = result
if (!result.isCancelled)
{
if(fbloginresult.grantedPermissions.contains("email"))
{
if((FBSDKAccessToken.currentAccessToken()) != nil){
FBSDKGraphRequest(graphPath: "me", parameters: ["fields": "id, name, first_name, last_name, picture.type(large), email"]).startWithCompletionHandler({ (connection, result, error) -> Void in
let bUserFacebookDict = result as! NSDictionary
id = bUserFacebookDict["id"]! as! String
urlPhoto = "https://graph.facebook.com/"+id+"/picture?width=500&height=500"
let credential = FIRFacebookAuthProvider.credentialWithAccessToken(FBSDKAccessToken.currentAccessToken().tokenString)
FIRAuth.auth()?.signInWithCredential(credential) { (user, error) in
self.currentUser.setCurrentUserState(user!.uid, _firstName: bUserFacebookDict["first_name"]! as! String, _name: bUserFacebookDict["last_name"]! as! String, _urlPhoto: urlPhoto, _email:bUserFacebookDict["email"]! as! String, _connected:true)
}
})
}
}
}
}
}
}
Then I add a listener in the ViewDidAppear method with perform segue after "connected" state.