AWS S3 File Download with Objective-C Successful Then Unsuccessful - ios

Question

I have a strange problem using AWS S3. The first time I call the code, files are downloaded from the S3 service as expected. The next time I call the code to download additional files, it hangs.
I am using version 2.1.2 of the AWS iOS SDK. I have downloaded and installed the SDK using cocoapods. I have read other threads on Stack Overflow and they do not address this issue.
The code:
static AWSStaticCredentialsProvider *credentialsProvider;
static AWSServiceConfiguration *configuration;
static AWSS3 *transferManager;
//This code is run when the object is instantiated
-(id)init
{
if ( self = [super init] ) {
credentialsProvider = [AWSStaticCredentialsProvider credentialsWithAccessKey:#“ACCESS KEY" secretKey:#“SECRET"];
configuration = [AWSServiceConfiguration configurationWithRegion:AWSRegionUSEast1 credentialsProvider:credentialsProvider];
[AWSServiceManager defaultServiceManager].defaultServiceConfiguration = configuration;
transferManager = [[AWSS3 alloc] initWithConfiguration:configuration];
}
return self;
}
-(UIImage *) getImageData:(NSString *)imageName
{
AWSS3 *transferManager = [[AWSS3 alloc] initWithConfiguration:configuration];
AWSS3GetObjectRequest *getImageRequest = [AWSS3GetObjectRequest new];
getImageRequest.bucket = #"quizontapimages/quizimages";
getImageRequest.key = imageName;
getImageRequest.key = [getImageRequest.key stringByAppendingString:#".png"];
BFTask *downloadTask1 = [[transferManager getObject:getImageRequest] continueWithExecutor:[BFExecutor mainThreadExecutor] withBlock:^id(BFTask *task) {
if(task.error)
{
NSLog(#"Error: %#",task.error);
}
else
{
NSData *data = [task.result body];
image = [UIImage imageWithData:data];
}
return nil;
}];
[downloadTask1 waitUntilFinished];
return image;
}
I have also tried commenting out the first line of getImageData method to use the initialized transferManager with the same results.
When I use AWS verbose logging on the successful download I get the following information:
2015-06-11 16:12:51.199 QuizOnTap[7362:538728] AWSiOSSDKv2 [Debug] AWSSignature.m line:241 | -[AWSSignatureV4Signer signS3RequestV4:] | Canonical request: [GET
/quizontapimages/quizimages/WABD_QSI_333x118.png
content-type:binary/octet-stream
host:s3.amazonaws.com
user-agent:aws-sdk-iOS/2.0.17 iPhone-OS/8.3 en_US
x-amz-content-sha256:*some key*
x-amz-date:20150611T211251Z
content-type;host;user-agent;x-amz-content-sha256;x-amz-date
*some key*]
2015-06-11 16:12:51.199 QuizOnTap[7362:538728] AWSiOSSDKv2 [Debug] AWSSignature.m line:248 | -[AWSSignatureV4Signer signS3RequestV4:] | AWS4 String to Sign: [AWS4-HMAC-SHA256
20150611T211251Z
20150611/us-east-1/s3/aws4_request
*some key*]
2015-06-11 16:12:51.493 QuizOnTap[7362:539182] AWSiOSSDKv2 [Debug] AWSURLResponseSerialization.m line:258 | -[AWSXMLResponseSerializer responseObjectForResponse:originalRequest:currentRequest:data:error:] | Response header: [{
"Accept-Ranges" = bytes;
"Content-Length" = 15947;
"Content-Type" = "image/png";
Date = "Thu, 11 Jun 2015 21:12:52 GMT";
Etag = "\"ff690cf7807b538278fc1590ce446785\"";
"Last-Modified" = "Sun, 31 May 2015 16:14:42 GMT";
Server = AmazonS3;
"x-amz-id-2" = "QIu6OWhmuO53z6Qgo+Q/4gsN4dQbyCAPbwS4QyDm/pmmSRXj8M5O4x5GoXMQq/rgSh0AKqt0uVk=";
"x-amz-request-id" = E0DB22A10F901130;
}]
2015-06-11 16:12:51.493 QuizOnTap[7362:539182] AWSiOSSDKv2 [Verbose] AWSURLResponseSerialization.m line:263 | -[AWSXMLResponseSerializer responseObjectForResponse:originalRequest:currentRequest:data:error:] | Response body: [(null)]
Later on in the process I call the same identical code that never returns from [downloadTask1 waitUntilFinished];. Below is the AWS verbose log for that transaction. Notice the long running operation warning as well.
2015-06-11 16:14:03.075 QuizOnTap[7362:538689] AWSiOSSDKv2 [Debug] AWSSignature.m line:241 | -[AWSSignatureV4Signer signS3RequestV4:] | Canonical request: [GET
/quizontapimages/quizimages/neat_square_1.png
content-type:binary/octet-stream
host:s3.amazonaws.com
user-agent:aws-sdk-iOS/2.0.17 iPhone-OS/8.3 en_US
x-amz-content-sha256:*some key*
x-amz-date:20150611T211403Z
content-type;host;user-agent;x-amz-content-sha256;x-amz-date
*some key*]
2015-06-11 16:14:03.075 QuizOnTap[7362:538689] AWSiOSSDKv2 [Debug] AWSSignature.m line:248 | -[AWSSignatureV4Signer signS3RequestV4:] | AWS4 String to Sign: [AWS4-HMAC-SHA256
20150611T211403Z
20150611/us-east-1/s3/aws4_request
*some key*]
2015-06-11 16:14:03.076 QuizOnTap[7362:538689] Warning: A long-running operation is being executed on the main thread.
Break on warnBlockingOperationOnMainThread() to debug.
2015-06-11 16:14:03.396 QuizOnTap[7362:540085] AWSiOSSDKv2 [Debug] AWSURLResponseSerialization.m line:258 | -[AWSXMLResponseSerializer responseObjectForResponse:originalRequest:currentRequest:data:error:] | Response header: [{
"Accept-Ranges" = bytes;
"Content-Length" = 4998;
"Content-Type" = "image/png";
Date = "Thu, 11 Jun 2015 21:14:04 GMT";
Etag = "\"7b27202a6560ed99277acebf2235ba89\"";
"Last-Modified" = "Fri, 22 May 2015 15:16:13 GMT";
Server = AmazonS3;
"x-amz-id-2" = "5TxaPQy8jblFr8qVXfiSg3pK0EfOqSdEWdykE0kfRKUdrfxvmxvYvzf0uXGYiXXliAG/DbM55tM=";
"x-amz-request-id" = 9F7BC6AC5494D285;
}]
2015-06-11 16:14:03.396 QuizOnTap[7362:540085] AWSiOSSDKv2 [Verbose] AWSURLResponseSerialization.m line:263 | -[AWSXMLResponseSerializer responseObjectForResponse:originalRequest:currentRequest:data:error:] | Response body: [(null)]

Answer 1

You are not retaining a strong reference to the transferManager object in - getImageData:. Please remember that - getObject: is an asynchronous method, and it returns immediately. You need to retain a strong reference to the service client until the request finishes processing.
If you use the AWS Mobile SDK for iOS 2.1.2, Xcode should give you a compiler warning for the use of - initWithConfiguration:. The method was deprecated to mitigate the misuse of the API such as this case. Please use + defaultS3TransferManager or + S3TransferManagerForKey: to retrieve the AWSS3TransferManager object.
(Also, the log indicates you are using 2.0.17 instead of 2.1.2.)