An iOS application is a compiled executable, along with a set of supporting files in a bundle. The application bundle is packaged into an archive file for installing onto a device or uploading to the App Store.

Most iOS applications to date have been written in Objective-C, a crossover between C and Smalltalk. With the advent of Swift, it is likely that many developers will move at least parts of their applications to Swift for performance and maintenance reasons. Although Objective-C is likely to be around for a while, it is clear that Swift is the future of iOS development, and probably OS X as well.

Applications contain a number of different types of files, which are used both at compile time and also at runtime. These files include: