I've been reading around trying to understand it. You can see here dictionaryWithObjects:objects the takes an array of Objects and Keys:

NSDictionary *dictionary = [NSDictionary dictionaryWithObjects:objects
                                                       forKeys:keys
                                                         count:count];

https://developer.apple.com/documentation/foundation/nsdictionary#overview

but initWithObjectsAndKeys_ only a single Object for input?