Different processing of% d in ObjectiveC compared to iOS

1st question here. I looked through the frequently asked questions, but could not find the answer.

I learned Obj C using Kochan’s book and it classifies% i for integers,% f for float,% d for double.

Using iOS, it seems like this sooner:% i and% d for integers and% f for float

Can someone confirm and possibly explain the rationale. I already looked at Apple's string programming guide.

Thanks in advance.