nil transfer utility after successful registration

[lmramirez]

State your question

I have set up my transfer utility like so:

        let credentialProvider = AWSBasicSessionCredentialsProvider(accessKey: uploadCredentials.accessKeyId,
                                                                     secretKey: uploadCredentials.secretAccessKey,
                                                                     sessionToken: uploadCredentials.sessionToken)

        guard let configuration = AWSServiceConfiguration(region: .USWest2, credentialsProvider: credentialProvider) else {
            completion?(.failure(.configurationFailed))
            return
        }
        configuration.sharedContainerIdentifier = config.appGroupId

        AWSS3TransferUtility.register(
            with: configuration,
            transferUtilityConfiguration: defaultTransferUtilityConfiguration,
            forKey: utilityKey
        ) { error in
            if let error = error {
                completion?(.failure(.failedToRegister(error: error)))
                return
            }

            guard let transferUtility = AWSS3TransferUtility.s3TransferUtility(forKey: utilityKey) else {
                // *** This code path should never be hit, but it sometimes is ****
                completion?(.failure(.utilityNotFound))
                return
            }

            let uploadService = VideoFileUploadService(config: config,
                                                       transferUtility: transferUtility,
                                                       videoId: videoId,
                                                       s3Bucket: s3Bucket)

            completion?(.success(uploadService))
        }

I've noticed in my application logs however, that on occasion, the transferUtility is nil. The docs indicate that this should only ever happen when there was an error in the registration, however, we can see that I am checking for the error in the lines preceding the getting of the transfer utility. How is this possible?

Which AWS Services are you utilizing?
S3

Provide code snippets (if applicable)

Environment(please complete the following information):

• SDK Version: 2.13.4
• Dependency Manager: cocoapods
• Swift Version : 5.0

Device Information (please complete the following information):

• Device: iPhone 10.4, but also many others
• iOS Version: 13.6
• Specific to simulators: No

[lawmicha]

Hi @lmramirez, Could you enable verbose logging?

AWSDDLog.sharedInstance.logLevel = .verbose
AWSDDLog.add(AWSDDTTYLogger.sharedInstance)

Do you have any relevant logs to share when it successfully registers but then retrieving it returns nil?

related code

1. init https://github.com/aws-amplify/aws-sdk-ios/blob/main/AWSS3/AWSS3TransferUtility.m#L389
2. retrieve for key https://github.com/aws-amplify/aws-sdk-ios/blob/main/AWSS3/AWSS3TransferUtility.m#L331

[wooj2]

Hi @lmramirez

I chatted with @royjit , and he noticed that the completion block could be called before the execution of registerS3TransferUtilityWithConfiguration:transferUtilityConfiguration:forKeycompletionHandler: completes.

To fix this, I submitted a version here which attempts to address your concern.

[lmramirez]

@wooj2 thanks for taking a look at this!

[wooj2]

Hi @lmramirez !

Thanks again for submitting this bug report. I've submitted the code change to main, and should be included as part of our next release. I will be optimistically closing this ticket for now, but feel free to re-open if you have any questions and/or concerns regarding this issue.

Thanks again!