messageHandler method Null safety

Future<String?> messageHandler(
  1. String? message
)

Handle lifecycle state messages and set the current app state

Implementation

Future<String?> messageHandler(String? message) async {
  AppState state = this.state;
  switch (message) {
    case 'AppLifecycleState.detached':
      state =
          this.state == AppState.unknown ? AppState.started : AppState.closed;
      break;

    case 'AppLifecycleState.resumed':
      state = this.state == AppState.started
          ? AppState.launched
          : AppState.resumed;
      break;

    case 'AppLifecycleState.paused':
      state = AppState.paused;
      break;

    case 'AppLifecycleState.inactive':
      state = AppState.inactive;
      break;
  }
  changeState(state);
  return message;
}