Restkit RKObjectManager requests timeout when downloading a lot of files - ios

Question

First off: I'm quite new to RestKit so perhaps this is an easy question to solve.
I am trying to download a lot of files. Currently I use the getObjectsAtPath:parameters:success:failure: method of RKObjectManager to fetch and map my objects towards restkit.
However, It seems as it starts some downloads prematurely and then timesout when they are in the queue.
The code I am using:
- (void)removeResponseAndRequestDescriptors
{
RKObjectManager *objectManager = [RKObjectManager sharedManager];
[objectManager.requestDescriptors enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
[objectManager removeRequestDescriptor:obj];
}];
[objectManager.responseDescriptors enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
[objectManager removeResponseDescriptor:obj];
}];
}
.
- (void)downloadAudioFileForAudio:(IBAudio *)audio
inBook:(IBBook *)book
downloadStatus:(void (^)(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead))downloadStatus
success:(void (^)(void))success
failure:(void (^)(NSError *error))failure
{
RKObjectManager *objectManager = [RKObjectManager sharedManager];
NSString *sessionID = (book.parent ? book.parent.user.session.sessionID : book.user.session.sessionID);
[objectManager.HTTPClient setDefaultHeader:#"Accept" value:#"application/octet-stream"];
[objectManager.HTTPClient setDefaultHeader:#"Session-Id" value:sessionID];
[objectManager.HTTPClient getPath:[IBProperties downloadAudioEndPointWithIsbn:book.isbn andAnchor:audio.anchor] parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSString *folderPath = [self folderPathForBook:book];
NSString *audioPath = [folderPath stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.mp3", audio.anchor]];
NSData *audioData = [NSData dataWithData:responseObject];
NSError *fileSystemSaveError;
[self saveFile:audioData toFilePath:audioPath error:&fileSystemSaveError];
if (fileSystemSaveError) {
failure(fileSystemSaveError);
return;
}
// Saving the context asap in case the app dies before it can autosave.
NSError *coreDataSaveerror;
[[[[RKObjectManager sharedManager] managedObjectStore] mainQueueManagedObjectContext] save:&coreDataSaveerror];
if (coreDataSaveerror) {
failure(coreDataSaveerror);
return;
}
[audio setFilePath:audioPath];
success();
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
failure(error);
}];
[objectManager.HTTPClient.operationQueue.operations.lastObject setDownloadProgressBlock:downloadStatus];
}
.
- (void)downloadAudioFiles
{
for (IBAudio *audio in self.book.bookData.audios) {
self.numberOfDownloads++;
[self.downloadPercentagesFiles addObject:[[IBDownloadStatusOfAFile alloc] init]];
NSInteger arrayIndex = [self.downloadPercentagesFiles count] - 1;
[[IBDataBackendFetcher sharedBackendFetcher] downloadAudioFileForAudio:audio inBook:self.book downloadStatus:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
IBDownloadStatusOfAFile *statusOfFile = [self.downloadPercentagesFiles objectAtIndex:arrayIndex];
statusOfFile.bytesRead = bytesRead;
statusOfFile.totalBytesRead = totalBytesRead;
statusOfFile.totalBytesExpectedToRead = totalBytesExpectedToRead;
[self updateDownloadProgress];
} success:^{
[self downloadDidComplete];
} failure:^(NSError *error) {
[self.dataProviderDelegate downloadDidFailWithError:error forBookDownloader:self];
}];
}
}
It seems as it starts all downloads at once, but the actuall download is not started. So the last downloads gets a timeout.
Is there a better way for do this to solve this problem?

Answer 1

All the downloads will run simultaneously, because you're making all the getPath: calls right in a row (they are asynchronous calls). Since each download takes a while to finish, this causes the timeout on the later calls.
If you want each download to occur only after the previous one completes, I would make a method called getNextAudioFile: and an iterator class property. Then, in both the success and failure blocks of getPath:, increment your iterator and call getNextAudioFile:.
Example code:
- (void)downloadAudioFiles
{
// No for loop
self.iterator = 0;
// your call to DownloadAudioFileForAudio: ... for the first audio goes here
}
- (void)downloadAudioFileForAudio:(IBAudio *)audio
inBook:(IBBook *)book
downloadStatus:(void (^)(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead))downloadStatus
success:(void (^)(void))success
failure:(void (^)(NSError *error))failure
{
// your code ...
[objectManager.HTTPClient getPath:[IBProperties downloadAudioEndPointWithIsbn:book.isbn andAnchor:audio.anchor] parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject){
// your code...
// increment and get the next file
self.iterator++;
[self getNextAudioFile];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
failure(error);
// increment and get the next file
self.iterator++;
[self getNextAudioFile];
}];
}
- (void)getNextAudioFile
{
if(self.iterator < [self.book.bookData.audios count]){
// make your downloadAudioFileForAudio: call for the next audio
}
}
That's the idea at least! Hope it helped.

Answer 2

Set the maximum number of concurrent operation on the queue to some reasonable value like 5.
[objectManager.HTTPClient.operationQueue setMaxConcurrentOperationCount:5];
(before you start any requests)