ios - core data not fetching when running on device

ios - core data not fetching when running on device

My app is running ok in the simulator, but when I run it on device, it
does not show the fetched results!
Code:
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Jobs"
inManagedObjectContext:_managedObjectContext];
[request setEntity:entity];
NSError *error = nil;
results = [_managedObjectContext executeFetchRequest:request error:&error];