Using delegates, operations, and queues

Question

I am using the AWS SDK for iOS to upload and download files to and from local hard drive to Amazon S3 storage. I am capable of making this work but I am unable to get the S3

Answer 1

It seems that the aws sdk behaves asynchronously after the time you set your delegate. So in order to have your asynchronous aws stuff work in a (asynchronous) NSOperation, you got to put some magic to wait for AWS to complete:

In your .h NSOperation file, add a boolean:

@interface UploadOperation : NSOperation  {
    @private
    BOOL        _doneUploadingToS3;
}

and in your .m file, your main method will look like this:

- (void) main
{   
    ....  do your stuff …..

    _doneUploadingToS3 = NO;

    S3PutObjectRequest *por = nil;
    AmazonS3Client *s3Client = [[AmazonS3Client alloc] initWithAccessKey:ACCESS_KEY withSecretKey:SECRET_KEY];
    s3Client.endpoint = endpoint;

    @try {
        por = [[[S3PutObjectRequest alloc] initWithKey:KEY inBucket:BUCKET] autorelease];
        por.delegate = self;
        por.contentType = @"image/jpeg";
        por.data = _imageData;

        [s3Client putObject:por];
    }
    @catch (AmazonClientException *exception) {
        _doneUploadingToS3 = YES;
    }

    do {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
    } while (!_doneUploadingToS3);

    por.delegate = nil;

    ....  continue with your stuff ….
}

do not forget to implement your delegate methods

-(void)request:(AmazonServiceRequest *)request didCompleteWithResponse:(AmazonServiceResponse *)response
{
    _doneUploadingToS3 = YES;
}

-(void)request:(AmazonServiceRequest *)request didFailWithError:(NSError *)error 
{
    _doneUploadingToS3 = YES;
}

-(void)request:(AmazonServiceRequest *)request didFailWithServiceException:(NSException *)exception 
{
    _doneUploadingToS3 = YES;
}

- (void) request:(AmazonServiceRequest *)request didSendData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
{
    // Do what you want
}

-(void)request:(AmazonServiceRequest *)request didReceiveResponse:(NSURLResponse *)response
{
    // Do what you want
}

-(void)request:(AmazonServiceRequest *)request didReceiveData:(NSData *)data
{
    // Do what you want
}

Note: this magic can work for any stuff that performs asynchronously but have to be implemented in a NSOperation.