Question

But it does have a lastObject, anybody know why?

Answer 1

My guess is because lastObject reduces more boilerplate code. You use [array lastObject] to replace either [array objectAtIndex:array.count - 1] or array[array.count - 1] using modern Objective-C syntax.

Whereas in the case of firstObject you can simply check [array objectAtIndex:0] or array[0].
It just helps streamline things to be able to call lastObject instead of typing out that function.

Update

As @Nathaniel Symer suggested in his comment above, firstObject has previously been available but only in private API (I believe since iOS 4). However, as of the release of the iOS 7 SDK, firstObject is now publicly available!