Question

I’m using this code to fetch something from Core data:

NSFetchRequest *req = [[NSFetchRequest alloc] initWithEntityName:@"Friend"];

NSString *predicateString = [NSString stringWithFormat:
                             @"identifier == %@", [[friendInfo objectForKey:@"id"] stringFromMD5]];
NSPredicate *predicate = [NSPredicate predicateWithFormat:predicateString];
req.predicate = predicate;

req.fetchLimit = 1;
NSError *requestError = nil;
NSArray *tmp = [self.managedObjectContext executeFetchRequest:req error:&requestError];

But it crashes on

NSString *predicateString = [NSString stringWithFormat:
                                 @"identifier == %@", [[friendInfo objectForKey:@"id"] stringFromMD5]];

If i remove the stringFromMD5 method call, it works.

NSString *predicateString = [NSString stringWithFormat:
                                     @"identifier == %@", [friendInfo objectForKey:@"id"]];

Any ideea why?
Thanks

Answer 1

please, try the following way, it might work well:

NSPredicate *_predicate = [NSPredicate predicateWithFormat:@"%K == %@", @"identifier", [[friendInfo objectForKey:@"id"] stringFromMD5]];