What language do iPhone apps use?

What language do iPhone apps use and where can i learn it (particularly for free)
Please be specific

Objective-C, somewhat modified for current times, it is otherwise dead language that seems to predate C++, and being Apple, all you need to know is Apple, Apple, and more Apple.

In the case of development is https://developer.apple.com/...apple.com/ it seems quite polished as Google does to Android.

IPhone apps are typically written in the C variant called "Objective C". I'm not sure if there are free development environments, but the official Apple IDE requires a paid subscription.

EDIT: It appears that the Xcode IDE is now freely available on the app store.

Mostly iPhone apps are developed on Objective C. But also its apps can be developed on C# and C++.

If you want to develop iPhone apps then learn Objective-C first then dive into the development of iPhone development. Here I have listed a good online resource for learning Objective-C language-

http://www.tutorialspoint.com/objective_c/index.htm

After learning Objective-C, you can learn iPhone app development from the official apple website. They are providing free education on iPhone app development. Here is the link for it-

https://developer.apple.com/...index.html

Apple developers are also providing the guidance from where you can go after learning from their website? Check the above link.

Tutorials Point website also have tutorials on iOS app development-
http://www.tutorialspoint.com/ios/index.htm