error exe-bad access after executing this line

Question

NSURL *url = [NSURL URLWithString: [NSString stringWithFormat:@"%@%@%@%@%@",[ConfigDB valueForKey:categoryURL], @"?ownerId=", 20,@"&userId=",64]];

can any one tell me wat wrong with this

Answer 1

For numbers you are supposed to use %d, not %@.

@"%@%@%d%@%d"