AWSS3TransferUtility uploading with Cognito authentication configuration issues?

Question

I have an app that authenticates with Cognito and has been working fine. Now I need to reuse the authentication and returned token to upload files to S3. My understanding is that AWSS3TransferUtility is the way to go at this point. Only it is not clear what needs to be done and how is the token to be passed to S3? Can anyone point to an example? Just using examples available suggesting to do:

let credentialsProvider = 
CredentialsProvider(regionType:region, identityPoolId:poolId)
let serviceS3Configuration = AWSServiceConfiguration(region:region, credentialsProvider: credentialsProvider)
AWSServiceManager.default().defaultServiceConfiguration = serviceS3Configuration

results in "Unauthenticated access is not supported for this identity pool" assuming that this is because token is not being used and S3 AWS service is not initialized correctly. But I do not see a way to set it ? what am I missing? I can see some examples suggesting setting logins property of credentialsProvider to AWSCognitoLoginProviderKey but seems to be outdated at this point. Any and all help would be greatly appreciated.

Answer 1

S3 configuration with Cognito is a little mysterious. The answers are in the docs but not entirely obvious. The core of getting this to work is registering your AWSMobileClient instance with the configuration.

Simplified code without error checking:

Boot up your AWSMobileClient:

AWSMobileClient.sharedInstance().initialize({ { userstate, error in
    if userstate != nil {
        registerAuthentication(credentialsProvider: AWSMobileClient.sharedInstance())
    }
})

Once completed pass the sharedInstance to AWSServiceConfiguration because AWSMobileClient is-a AWSCredentialsProvider

let DefaultTransferUtilityKey = "DEFAULT_AUTH_KEY"
func registerAuthentication(credentialsProvider: AWSCredentialsProvider) {
    /// only do this once per app launch 

    /// assumes you're using the plist config method
    guard let s3tranferInfo = AWSInfo.default().defaultServiceInfo("S3TransferUtility"),
        let bucketName = s3tranferInfo.infoDictionary["Bucket"] as? String else {
            assertionFailure("failed to load /S3TransferUtility/Bucket key  - is awsconfiguration.json correct ?")
            return
    }

    let transferConfig = AWSS3TransferUtilityConfiguration()
    transferConfig.bucket = bucketName
    if let serviceconfiguration = AWSServiceConfiguration(region: s3tranferInfo.region, credentialsProvider: credentialsProvider) {
        AWSS3TransferUtility.register(with: serviceconfiguration, transferUtilityConfiguration: transferConfig, forKey: DefaultTransferUtilityKey)
    }
}

and once that registration is actually finished you can access the transfer utility via the common key string.

lazy var transferUtility: AWSS3TransferUtility = {
    let utility = AWSS3TransferUtility.s3TransferUtility(forKey: DefaultTransferUtilityKey)
    return utility
}()

Bucket name and region could be strings also but if you're using AWSMobileClient you probably have the plist setup.