Register a callback that will be called whenever NamiCustomerManager.login or NamiCustomerManager.logout is called with results from those calls.

NamiCustomerManager.registerAccountStateHandler { accountStateAction, success, error in
     if success {
         if accountStateAction == .login {
           // logged in
         } else if accountStateAction == .logout {
           // logged out
         }        
     } else {
       // an error occured
     }
}
NamiCustomerManager.registerAccountStateHandler { accountStateAction, success, error ->
    if (success) {
        if (accountStateAction == AccountStateAction.LOGIN) {
            Log.d(LOG_TAG, "User is logged in")
        } else if (accountStateAction == AccountStateAction.LOGOUT) {
            Log.d(LOG_TAG, "User is logged out")
        }
    } else if (error != null) {
        if (accountStateAction == AccountStateAction.LOGIN) {
            Log.d(LOG_TAG, "There was an error logging in. Error - ${error}")
        } else if (accountStateAction == AccountStateAction.LOGOUT) {
            Log.d(LOG_TAG, "There was an error logging out. Error - ${error}")
        }
    }
}
NamiCustomerManager.registerAccountStateHandler()
    .listen((accountState) {
  print("AccountStateHandler triggered");

  if (accountState.success) {
    if (accountState.accountStateAction == AccountStateAction.login) {
      print("Login success");
    } else
    if (accountState.accountStateAction == AccountStateAction.logout) {
      print("Logout success");
    }
  } else {
    if (accountState.accountStateAction == AccountStateAction.login) {
      print("Login error - ${accountState.error}");
    } else
    if (accountState.accountStateAction == AccountStateAction.logout) {
      print("Logout error - ${accountState.error}");
    }
  }
});