Compiling a C++ program to an IOS application

I run Xcode 4 so I don't know how well this applies:

Xcode and the LLVM complier support C++, the newer the versions, the more they support, so your support is probably be less.

Several of the example projects that Apple has in their documentation, have .mm files They are C++ code compiled and linked into the app.

Right now, I'm looking through the avTouch app.

Open Xcode, click on Organizer, search for avTouch, open AudioViews, look at files with '.mm'

I know you asked about 'hello world' I don't know exactly how an app would be developed entirely in C++ or if it can be done, but this might point you in the right direction.

 

You either compile a C++ library as a static library (.a) or mix C++ classes/functions with Objective-C code
by renaming your files with the .mm extension.

 

I don't know any offhand, only Google can tell.


If you want some brief instructions on how to create a static library with XCode 4.3:

1. In your iPhone project, click on the "Add Target" icon. It's a big icon found next to the "Validate Settings" icon.

2. Choose the template iOS -> Framework & Library -> Cocoa Touch Static Library.

3. Your new static library should now be listed under "Targets" in your Project window.
Click on it, and goto Build Phases -> Compile Sources. This is where all of your C++ source files go.
Add them here.

4. Goto Build Settings -> Search Paths -> Header Search Paths. Add any paths to your C++ header files.

5. It should be ready to compile, so build it. If everything goes well, you should see a static library
file called "foo.a" in your project folder window.


How to integrate it into your iPhone application:

1. In your iPhone project, add "foo.a" to Build Phases -> Link Binary With Libraries.

2. Any Objective-C source file (.m) that you include the C++ header files should be renamed to (.mm).

3. Let's say your C++ library consists of a single C++ class called MyWorld.
What I would do is dynamically allocate a single C++ instance of this class in the viewDidLoad method:

myWorld = new MyWorld();

Use this pointer everywhere to call any functions, pass/retrieve data, etc...

4. When done, de-allocate it in the dealloc method:
if(myWorld) {
delete myWorld;
myWorld = NULL;
}


If you ever use the physics engine called Box2D, then this is exactly what you need to do
to use it with your iPhone app. Box2D is a 2D physics engine written in C++.