executeFetchRequest crashes on third call

Question

I have a weird problem in my Objective-C code. I have a View Controller where I call my own loadData method in "viewWillAppear". This works cool until the view becomes visible the third time.

Than the app crashes without any exceptions or other hints when I call

NSArray *storeListArray = [managedObjectContext executeFetchRequest:fetchRequest error:&error];

I checked that the managedObjectContext is not accidentally released somewhere else. But that seems not be the case. The fetchRequest is created right before the call above. I guess it crashes somewhere inside the executeFetchRequest method.

Has anybody an idea where I could look for the error? What is really bugging me is the fact that it reproducible happens on the third call.

Answer 1

Allright... I solved the problem (I guess). As far as I can see, the problem was the "error" of the call.

I made a stupid mistake by not initializing the NSError object before the call. So here is what works for me now:

NSError *error = nil;
NSArray *storeListArray = [MOC executeFetchRequest:fetchRequest error:&error];

Before it was only

NSError *error;

That's what I found in many examples by the way. But it seems like that was at least a part of the problem.

My whole code looks like this now:

MyAppDelegate *app = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];

NSManagedObjectContext *MOC = [app managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Store" inManagedObjectContext:MOC];
[fetchRequest setEntity:entity];

NSSortDescriptor *streetDescriptor = [[NSSortDescriptor alloc] initWithKey:@"street" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:streetDescriptor, nil];    
[fetchRequest setSortDescriptors:sortDescriptors];

NSError *error = nil;
NSArray *storeListArray = [MOC executeFetchRequest:fetchRequest error:&error];

Maybe that helps someone.