system() call in cocoa app

In my cocoa app I have to call system() function to launch an external app. The command I use is:

system("./main &");
 

If I run the app from Xcode, it works fine, because I know the folder where to put main.

If I create an archive, and distribute my .app application, system() can't find "main". Where I have to put it?? Or otherwise, how can I run an app using "./" when I'm not in the folder the application is?

Thanks

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