gistfile1.txt

    NSData *imageData = UIImageJPEGRepresentation(image, 0.7);
    NSString *signature = <signature generated on our server>
    NSString *AWSAccessKeyId = <access key generated on our server>
    NSString *policy = <encoded policy string generated on our server>
    NSString *key = <target relative path + filename of image>
    NSString *S3BucketName = @"bucket_name";
    NSString *content_type = @"image/jpeg";
    NSString *filename = <filename of image>;
    
    // Create the headers.
    NSMutableDictionary *headers = [[NSMutableDictionary alloc] init];
    [headers setObject:content_type forKey:@"Content-Type"];
    [headers setObject:AWSAccessKeyId forKey:@"AWSAccessKeyId"];
    [headers setObject:key forKey:@"key"];
    [headers setObject:policy forKey:@"policy"];
    [headers setObject:signature forKey:@"signature"];
    [headers setObject:@"public-read" forKey:@"acl"];
    
    AFHTTPRequestSerializer *serializer = [[AFHTTPRequestSerializer alloc] init];
    NSURLRequest *request = [serializer multipartFormRequestWithMethod:@"POST" URLString:[NSString stringWithFormat:@"http://%@.s3.amazonaws.com/", S3BucketName] parameters:headers constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
        [formData appendPartWithFileData:imageData name:@"file" fileName:filename mimeType:@"image/jpeg"];
    }];

//Use an AFHTTPRequestOperation to execute the request