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While the Mac App Store is definitely a great option to distribute your application, it's not for everyone. Applications that can't take advantage of sandboxing or other Apple-imposed restrictions will need to find another route for distribution.
In this tutorial, I'll show you how to create a DMG-based installer for your application that's perfectly optimized for Retina displays.
While you could theoretically accomplish everything I discuss in this tutorial without any additional software, an app for hiding and unhiding files, like invisibliX, as well as one for editing images, like Pixelmator, will save you loads of time and effort.
Finally, if you're looking for more information on the tiffutil command that's used to create multi-representational TIFF images, check out the high resolution guidelines, from Apple's Developer Library.