AFJSONRequestOperation Crash data parameter is nil - ios

Question

I'm experiencing a strange issue that only happens intermittently when I run my app. I'm attempting to pull down JSON from two different sources, using AFNetworking. Occasionally, when the operations are running, the app will crash with *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'data parameter is nil' landing on json_request_operation_processing_queue.
I'm hoping this isn't a problem with AFNetworking, and I'm just doing something incorrectly. Here are my methods that I think are relavent (JSONManager extends AFHTTPClient):
+ (JSONManager *) sharedJSONManager {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_sharedJSONManagerInsance = [[JSONManager alloc] initWithBaseURL:[NSURL URLWithString:sourceUrl1]];
});
return _sharedJSONManagerInsance;
}
- (void) loadOperations {
_sharedJSONManagerInsance.operations = [NSMutableArray arrayWithCapacity:2];
[_sharedJSONManagerInsance.operations addObject:[self fetchJSON:sourceUrl1]];
[_sharedJSONManagerInsance.operations addObject:[self fetchJSON:sourceUrl2]];
}
- (void) executeOperations {
[_sharedJSONManagerInsance loadOperations];
_sharedJSONManagerInsance.fetchedStories = [[NSMutableArray alloc] init];
[self enqueueBatchOfHTTPRequestOperations:operations
progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
NSLog(#"Finished %d of %d", numberOfFinishedOperations, totalNumberOfOperations);
}
completionBlock:^(NSArray *operations) {
[[CoreDataManager sharedManager] persistFetchedStories:_sharedJSONManagerInsance.fetchedStories];
_sharedJSONManagerInsance.operations = nil;
NSLog(#"All operations finished");
}];
}
- (AFHTTPRequestOperation *)fetchJSON:(NSString*)requestUrl {
NSURL* jsonUrl = [NSURL URLWithString:requestUrl];
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:jsonUrl];
AFJSONRequestOperation *operation = nil;
operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
if([requestUrl isEqualToString:sourceUrl1]) {
NSArray* arr = [[JSON valueForKeyPath:#"data"] valueForKey:#"children"];
for (NSDictionary *item in arr) {
FetchedStory* fs = [[FetchedStory alloc] init];
fs.title = [[item valueForKey:#"data"]valueForKey:#"title"];
fs.url = [[item valueForKey:#"data"]valueForKey:#"url"];
fs.score = [[item valueForKey:#"data"]valueForKey:#"score"];
fs.source = #"source1";
[self.fetchedStories addObject:fs];
}
}
else if([requestUrl isEqualToString:sourceUrl2]) {
NSArray* arr = [JSON valueForKeyPath:#"items"];
for (NSDictionary *item in arr) {
FetchedStory* fs = [[FetchedStory alloc] init];
fs.title = [item valueForKey:#"title"];
fs.url = [item valueForKey:#"url"];
NSString* scoreString = [item valueForKey:#"score"];
if(scoreString != nil && [scoreString length]!=0) {
NSRange spaceRange = [scoreString rangeOfString:#" "];
scoreString = [scoreString substringToIndex:spaceRange.location];
fs.score = [NSDecimalNumber decimalNumberWithString:scoreString];
fs.source = #"source2";
[self.fetchedStories addObject:fs];
}
}
}
} failure:nil];
return operation;
}
The crash happens before "All operations finished" logs to the console. Again, this only happens some of the time.

Answer 1

It looks like this is a bug with AFJSONRequestOperation's responseJSON method. I added a nil check and that seems to be a good bandaid.

Answer 2

Actually you forget to set HTTP Method Parameter it should be like this:
[request setHTTPMethod:#"get"]; // post, patch ....