Why and when should I use C/C++ code in iOS application?

Question

When and especially why should I switch from Objective-C to C or C++ when I develop on iOS platform. I'm sure I'm missing something but as far as I can see Apple wants developers to use Objective-C everywhere in Mac/iOS environment so why would I go with C/C++?

One note, though, I'm NOT talking about GAME DEVELOPMENT. In case of games I realize what are the advantages. I just don't get when I want to use C if I develop, for example, a client for a server or something like that (once again, not a game). All the classes I need already there and all of them in Objective-C.

Answer 1

Objective C is a strict superset of ANSI C, so an Objective C programmer is very likely already doing a significant amount of programming in C. In fact, many Mac and iOS APIs (audio, graphics, etc.) are C interfaces and/or use C data types.

A few of the reasons to do something in C, of things that are possible in both the superset and subset languages, might include performance and portability. There is a small amount of runtime overhead to Objective C messaging that is completely unsuitable for the inner loops of real-time audio or video image processing, etc. For portability, one can often use well encapsulated C code in iOS, Linux, Android NDKs, WebOS PDKs, & etc. And occasionally the Objective C wrappers for an OS service won't offer all the flexibility of some underlying C API.

The only reason I can see to use C++ for an iOS app might be to use some legacy C++ code and maintain some consistency of style with that code for readability, maintainability, etc.

For an iOS app where performance, or any portable code reuse is not important, there are few reasons to not just use Objective C (with its included C language), as that is what the most current documentation, tools, frameworks, and APIs for iOS are supported on.

Answer 2

The main advantage is portability. A chunk of code written in C++ or C can, when appropriate measures are taken, be very easily wrapped up and used in iOS or Android, or Blackberry, etc... Many 3rd party libraries go this route for that reason (Zebra Crossing and OpenCV come to mind immediately).

Another reason (and I would argue bad reason) is simply that a developer is comfortable in C or C++ and wants to avoid learning Objective-C as much as possible.

Answer 3

The only reasons I can think of are (a) you have an existing C++ codebase that you want to re-use (and don't want to have to rewrite it all in Objective C), or (b) you really like C++ and/or really don't like Objective C.