Handling Firebase 5 Authentication Errors In Swift 4

Question

We have an existing project which has been recently updated to Firebase 5, Swift 4 and our Authentication error handling doesn't appear to be working.

I found several answers here on SO, but those no longer appear to be applicable:

Error Handling

Auth Codes

Suppose a user is logging in and they enter a valid email and invalid password, which are passed to the following code to authenticate

Auth.auth().signIn(withEmail: user, password: pw, completion: { (auth, error) in
    if error != nil {
        let errDesc = error?.localizedDescription
        print(errDesc!) //prints 'The password is invalid'
        let err = error!
        let errCode = AuthErrorCode(rawValue: err._code)
        switch errCode {
        case .wrongPassword: //Enum case 'wrongPassword' not found in type 'AuthErrorCode?'
            print("wrong password")
        default:
            print("unknown error")
        }
    } else {
        print("succesfully authd")
    }
})

Previously, we could use FIRAuthErrorCode to compare to possible errors such as FIRAuthErrorCodeInvalidEmail, FIRAuthErrorCodeWrongPassword etc but the code posted above won't compile due to this the error on this line

case .wrongPassword:   Enum case 'wrongPassword' not found in type 'AuthErrorCode?'

oddly, if I use autofill by typing

case AuthErrorCode.wr

.wrongPassword is a selectable option and when seleted the compiler shows

Enum case 'wrongPassword' is not a member of type 'AuthErrorCode?'

even though it was a selectable option.

Answer 1

You should handle error code by converting Error into NSError.

  Auth.auth().signIn(withEmail: email, password: password) { (authResult, error) in
    switch error {
    case .some(let error as NSError) where error.code == AuthErrorCode.wrongPassword.rawValue:
      print("wrong password")
    case .some(let error):
      print("Login error: \(error.localizedDescription)")
    case .none:
      if let user = authResult?.user {
        print(user.uid)
      }
    }
  }