# refreshToken method Null safety

Future<OAuthToken> refreshToken(

1. {required OAuthToken oldToken,
2. String? redirectUri,
3. String? appKey}

)

기존 토큰(`oldToken`)을 갱신합니다.

## Implementation

    Future<OAuthToken> refreshToken({
      required OAuthToken oldToken,
      String? redirectUri,
      String? appKey,
    }) async {
      final data = {
        Constants.refreshToken: oldToken.refreshToken,
        Constants.grantType: Constants.refreshToken,
        Constants.clientId: appKey ?? KakaoSdk.platformAppKey,
        Constants.redirectUri: redirectUri ?? await _platformRedirectUri(),
        ...await _platformData()
      };
      final newToken = await _issueAccessToken(data, oldToken: oldToken);
      await _tokenManagerProvider.manager.setToken(newToken);
      return newToken;
    }