How to associate self hosted content with transaction?

Question

I'm trying to add in-app purchase feature to my application and I want to download contents that I host in my own server. RMStore provides an API to do this, however I couldn't figure out how to do it.

Documentation says:

RMStore delegates the downloading of self-hosted content via the optional contentDownloader delegate. You can provide your own implementation using the RMStoreContentDownloader protocol:

- (void)downloadContentForTransaction:(SKPaymentTransaction*)transaction
                              success:(void (^)())successBlock
                             progress:(void (^)(float progress))progressBlock
                              failure:(void (^)(NSError *error))failureBlock;

Call successBlock if the download is successful, failureBlock if it isn't and progressBlock to notify the download progress. RMStore will consider that a transaction has finished or failed only after the content downloader delegate has successfully or unsuccessfully downloaded its content.

And here is the protocol (from RMStore.h):

@protocol RMStoreContentDownloader <NSObject>

/**
 Downloads the self-hosted content associated to the given transaction and calls the given success or failure block accordingly. Can also call the given progress block to notify progress.
 @param transaction The transaction whose associated content will be downloaded.
 @param successBlock Called if the download was successful. Must be called in the main queue.
 @param progressBlock Called to notify progress. Provides a number between 0.0 and 1.0, inclusive, where 0.0 means no data has been downloaded and 1.0 means all the data has been downloaded. Must be called in the main queue.
 @param failureBlock Called if the download failed. Must be called in the main queue.
 @discussion Hosted content from Apple’s server (@c SKDownload) is handled automatically by RMStore.
 */
- (void)downloadContentForTransaction:(SKPaymentTransaction*)transaction
                              success:(void (^)())successBlock
                             progress:(void (^)(float progress))progressBlock
                              failure:(void (^)(NSError *error))failureBlock;

@end

Simply it says, downloads the self-hosted content associated to the given transaction. How do I associate the self-hosted to transaction?

Answer 1

Here what I did. Obviously you need to add RMStore.h and the protocol RMStoreContentDownloader in the class where you run this method. It works, although I did not understand how it is managed the progressBlock (maybe my download is too short?)...

- (void)downloadContentForTransaction:(SKPaymentTransaction*)transaction
                          success:(void (^)())successBlock
                         progress:(void (^)(float progress))progressBlock
                          failure:(void (^)(NSError *error))failureBlock
{
    //the product purchased
    NSString *productID = transaction.payment.productIdentifier;


    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

    //HERE IS WHERE TO INSERT THE URL
    NSURL *URL = [NSURL URLWithString:@"http://example.com/download.zip"];
    NSURLRequest *request = [NSURLRequest requestWithURL:URL];

    NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {
    NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
    return [documentsDirectoryURL URLByAppendingPathComponent:[response suggestedFilename]];
    } completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
    if (error == nil)
        NSLog(@"File downloaded to: %@", filePath);
        successBlock();
    else
        NSLog(@"Error in download: %@", error.localizedDescription);
        failureBlock();
    }];
    [downloadTask resume];
    [manager setDownloadTaskDidWriteDataBlock:^(NSURLSession *session,    NSURLSessionDownloadTask *downloadTask, int64_t bytesWritten, int64_t totalBytesWritten, int64_t totalBytesExpectedToWrite)
    {
        float percentDone = (((float)((int)totalBytesWritten) / (float)((int)totalBytesExpectedToWrite))*100);
        progressBlock(percentDone);
    }];

}

Then the method will be called by RMStore at the right moment!

Hope it helps!

Answer 2

Does the content you are trying to provide via in-app purchase unique for each transaction? If it is unique for every transaction, you should pass transaction id to your server and download the content generated for only this transaction id. Otherwise, for each transaction download the content without passing transaction id. For both cases, you should call successBlock or failureBlock at the end of download process. Optionally, you can call progressBlock each time you want to update progress.