Firebaseui-ios: Problem with Facebook Login: Unsuccessful debug_token response from Facebook: - The App_id in the input_token did not match the Viewing App

[boxerboxer]

Swift
iOS 12.1
Using Firebase (5.12.0)
Using FirebaseAuth (5.0.5)
Using FirebaseAuthInterop (1.0.0)
Using FirebaseCore (5.1.7)
Using FirebaseUI (5.2.2)
Using FBSDKCoreKit (4.38.1)
Using FBSDKLoginKit (4.38.1)
cocoapods-1.5.3

I've followed these two guides carefully:

https://firebase.google.com/docs/auth/ios/firebaseui?authuser=1
and
https://github.com/firebase/FirebaseUI-iOS/blob/master/FirebaseAuthUI/README.md

But they seem to differ on one key step:

The github guide says I should use:

func authUI(_ authUI: FUIAuth, didSignInWithAuthDataResult authDataResult: AuthDataResult?, error: Error?) { // handle user (authDataResult.user) and error as necessary }

While the Firebase guide asks for:
After you present the authentication view and the user signs in, the result is returned to the FirebaseUI Auth delegate in the didSignInWithUser:error: method:
SwiftObjective-C

func authUI(_ authUI: FUIAuth, didSignInWith user: FIRUser?, error: Error?) { // handle user and error as necessary }

Xcode gives me errors while suing didSignWithAuthDataResult, so I either have to add @noobjc (which causes the method to never be called) or @objc(authUI:didSignInWithAuthDataResult:error:) func authUI(_ authUI: FUIAuth, didSignInWith authDataResult: AuthDataResult?, error: Error?) { (which ends up in an error similar to using disSignInWithUser as seen below)

When I use didSignInWithUser I get the following error after logging into Facebook:

"An internal error has occurred, print and inspect the error details for more information."

with this full error description:

Printing description of error:
▿ Optional<Error>
  - some : Error Domain=FIRAuthErrorDomain Code=17999 "An internal error has occurred, print and inspect the error details for more information." UserInfo={error_name=ERROR_INTERNAL_ERROR, NSLocalizedDescription=An internal error has occurred, print and inspect the error details for more information., NSUnderlyingError=0x600000b051d0 {Error Domain=FIRAuthInternalErrorDomain Code=3 "(null)" UserInfo={FIRAuthErrorUserInfoDeserializedResponseKey={
    code = 400;
    errors =     (
                {
            domain = global;
            message = "Unsuccessful debug_token response from Facebook: {\"error\":{\"message\":\"(#100) The App_id in the input_token did not match the Viewing App\",\"type\":\"OAuthException\",\"code\":100,\"fbtrace_id\":\"FrWC0+oiUWC\"}}";
            reason = invalid;
        }
    );
    message = "Unsuccessful debug_token response from Facebook: {\"error\":{\"message\":\"(#100) The App_id in the input_token did not match the Viewing App\",\"type\":\"OAuthException\",\"code\":100,\"fbtrace_id\":\"FrWC0+oiUWC\"}}";
}}}}

Also this method is never called.

`func application(_ app: UIApplication, open url: URL,
                     options: [UIApplicationOpenURLOptionsKey : Any]) -> Bool {
        let sourceApplication = options[UIApplicationOpenURLOptionsKey.sourceApplication] as! String?
        if FUIAuth(uiWith: Firebase.auth())?.handleOpen(url, sourceApplication: sourceApplication) ?? false {
            return true
        }
        // other URL handling goes here.
        return false
    }

What can be causing this problem?

Also, if I cannot manage to get this working with Firebase UI, can I implement Facebook login manually with Firebase but use Firebase UI Auth for all the other authentication mentods?

[boxerboxer]

Note that email signup works fine and I'm not calling the default Auth UI because it looks for GoogleService-Info.plist whereas I have to plist files, one for Development and the other for Production. So, here's the code I use:

`let authUI = FUIAuth(uiWith: Firebase.auth())
guard let _ = authUI else {
return
}
authUI?.delegate = self

    let providers: [FUIAuthProvider] = [
        FUIFacebookAuth()
    ]

    authUI!.providers = providers

    let authViewController = authUI!.authViewController()
    present(authViewController, animated: true, completion: nil)`

The singleton Firebase, calls these:

`@objc static func app() -> FirebaseApp {
return FirebaseApp.app(name: environment.rawValue)!
}

@objc static func auth() -> Auth {
    return Auth.auth(app: app())
}`

[morganchen12]

The GitHub guide is more recent, but both should work. The one on the Firebase site just references a deprecated method.

Are you able to integrate Facebook manually? The debug token issue shouldn't be a FirebaseUI-specific issue.

[boxerboxer]

Thank you. The problem was with the wrong Facebook app id.

[leonaburime]

For anyone running into this issue in the future the problem is an internal Expo issue that is references here