Generally, what you'd do is store a copy of the file in the Resources
directory of your application bundle. From there, it depends on what kind of application you have. If it's a single document application (like iPhoto, for example), You could copy the file to the ~/Application Support/Your Application
directory so that your app will open it by default.
Take a look inside the application delegate class (I'm assuming you're using the template provided with Xcode?) to see how it generates the path to the application file. You basically just have to make sure that the file exists at that path when the application starts up.
In this case, NSFileManager
and the pathForResource:ofType:
method of NSBundle
are your friends.