Photos Being Returned Randomly From AFImageRequestOperation - ios

Question

In the following code snippet I am authenticating with a web service and retrieving very tiny photos (filesize < 50kb) into core data. This works relatively ok but randomly it doesn't return any photo.
I have checked the URLs that I am passing to it for each photo are correct and resolve correctly. I need it to return a photo everytime.
LogInfo("IMPORTING PHOTO BINARY DATA.");
NSString *photoURL = value;
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:photoURL]];
AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:request imageProcessingBlock:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
LogInfo(#"RETRIEVED PHOTO IN setValue.");
NSData* imageData = [NSData dataWithData:UIImagePNGRepresentation(image)];
LogInfo(#"PUTTING THE IMAGE INTO CORE DATA IN setValue.");
[managedObject setValue:imageData forKey:#"personphoto"];
}failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
LogInfo(#"ERROR GETTING PHOTO IN setValue.");
}];
[operation setAuthenticationChallengeBlock:^(NSURLConnection *connection, NSURLAuthenticationChallenge *challenge) {
NSURLCredential *newCredential = [NSURLCredential credentialWithUser:self.strSPUser password:self.strSPPW persistence:NSURLCredentialPersistenceForSession];
[challenge.sender useCredential:newCredential forAuthenticationChallenge:challenge];
}];
NSOperationQueue* operationQueue = [[NSOperationQueue alloc] init];
[operationQueue addOperation:operation];
[managedObject setValue:value forKey:#"personimageurl"];
The "personimageurl" gets set correctly everytime but the "personphoto" in core data does not get updated with the image data every time.
[EDIT]
After some further testing I have noticed that when I have a higher bandwidth connection that more of the images are downloaded and stored in core data than when I have a slower connection. This would point to something being wrong with AFImageRequestOperation performance.
[EDIT
I've changed my code around to work as follows:
IN MYHTTPCLIENT.M :
- (void)downloadImageWithCompletionBlock:(void (^)(UIImage *downloadedImage))completionBlock identifier:(NSString *)identifier {
NSString* urlString = identifier;
AFImageRequestOperation* operation = [AFImageRequestOperation imageRequestOperationWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlString]] imageProcessingBlock:nil
success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image)
{
LogInfo(#"SUCCESS GETTING PHOTO: %#", response);
completionBlock(image);
}
failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
LogInfo(#"ERROR GETTING PHOTO IN downloadImageWithCompletionBlock.");
}];
[operation setAuthenticationChallengeBlock:^(NSURLConnection *connection, NSURLAuthenticationChallenge *challenge) {
NSURLCredential *newCredential = [NSURLCredential credentialWithUser:self.strSPUser password:self.strSPPW persistence:NSURLCredentialPersistenceForSession];
[challenge.sender useCredential:newCredential forAuthenticationChallenge:challenge];
}];
[self enqueueHTTPRequestOperation:operation];
}
Then I call the above method in MYSYNCENGINE.M as follows:
[[OLHTTPClient sharedClient] downloadImageWithCompletionBlock:^(UIImage *downloadedImage) {
LogInfo(#"RETRIEVED PHOTO IN setValue.");
NSData* imageData = [NSData dataWithData:UIImagePNGRepresentation(downloadedImage)];
[managedObject setValue:value forKey:#"olpersonimageurl"];
LogInfo(#"PUTTING THE IMAGE INTO CORE DATA IN setValue.");
[managedObject setValue:imageData forKey:#"olpersonphoto"];
} identifier:photoURL];
Now when I am connected on a high bandwidth connection I get most of the images returned but they are never returned the first time I call the above method. With every subsequent call the images are returned.
No errors are received at all and debugging shows that every image is returned successfully but not all of the images end up in core data.
Any ideas why this is happening?
[END EDIT]

Answer 1

Easy solution: don't store image data in Core Data.
NSURLCache provides in-memory as well as disk-based storage, and respects HTTP cacheing rules. Storing image URLs for each managed object and loading images on-demand is a likely a much better way to go.