iOS: Fatal error: Unexpectedly found nil while unwrapping an Optional value: file Pods/AWSMobileClient/AWSAuthSDK/Sources/AWSMobileClient/AWSMobileClientExtensions.swift, line 211

[danielvtan]

Describe the bug
iOS app crash when logging in

Expected behavior
Should be able to login

Platform
Amplify Flutter current supports iOS and Android. This issue is reproducable in (check all that apply):
[] Android
[X] iOS

Smartphone (please complete the following information):

• Device: iPhone 8
• OS: iOS 13.3

Additional context
Add any other context about the problem here.

Fatal error: Unexpectedly found nil while unwrapping an Optional value: file 
<project location>Pods/AWSMobileClient/AWSAuthSDK/Sources/AWSMobileClient/AWSMobileClientExtensions.swift, line 211

Same project run in android is working

dependencies:
...
  amplify_core: '<1.0.0'
  amplify_auth_cognito: '<1.0.0'

    "UserAgent": "aws-amplify-cli/2.0",
    "Version": "1.0",
    "auth": {
        "plugins": {
            "awsCognitoAuthPlugin": {
                "IdentityManager": {
                    "Default": {}
                },
                "CredentialsProvider": {
                    "CognitoIdentity": {
                        "Default": {
                            "PoolId": "ap-southeast-1:---",
                            "Region": "ap-southeast-1"
                        }
                    }
                },
                "CognitoUserPool": {
                    "Default": {
                        "PoolId": "ap-southeast-1_---",
                        "AppClientId": "---",
                        "AppClientSecret": "---",
                        "Region": "ap-southeast-1"
                    }
                },
                "Auth": {
                    "Default": {
                        "authenticationFlowType": "USER_SRP_AUTH"
                    }
                }
            }
        }
    }
}''';

[danielvtan]

Issue was. we had a third party flutter cognito plugin installed. removing it resolved the issue

[pal]

I get this same error in iOS and only have these deps:

dependencies:
  flutter:
    sdk: flutter

  amplify_core: '<1.0.0'
  amplify_auth_cognito: '<1.0.0'
  amplify_analytics_pinpoint: '<1.0.0'

  cupertino_icons: ^0.1.3

dev_dependencies:
  flutter_test:
    sdk: flutter

This is the stock todo-app, but with the addition of sign-in code:

SignInResult res = await Amplify.Auth.signIn(
  username: 'myusername',
  password: 'mysupersecurepassword',
);

Any ideas?

[danielvtan]

Have you tried running

pub get
flutter clean
flutter run

this usually solve dependency issues if your pubspec is correct