C, Obj-C, C++, some questions argh

[silentownage001]

After searching Google and this forum I have still not been able to fully find the answer.

As of now though I intend to write programs for iOS (I have some ideas) and later OS X if I think of anything.

Currently reading Objective-C Programming Big Nerd Ranch Guide. When I'm done I will hopefully have a good understanding of C and Objective-C after reading the advanced parts.

So far I'm still on Command Line Tools. I know you can select C++. I was wondering though that since you need Objective-C for Cocoa (from my understanding), what would C++ be used for? At least for iOS and OS X. I've seen someone say that it's a good compromise. Not entirely sure for what though.

Whatever language I learn next though, will most likely be dictated by what I want to program for next. I do wonder when I'll actually use C but understanding it will be quite helpful.