The Chameleon Project to bring iOS apps to the Mac
A new open source project, Chameleon, is bridging the gap between iPhone and iPad applications and Mac OS X desktop applications. Anybody that has developed an iOS application has probably used UIKit, the framework provided by Apple that provides the Apple designed graphical interface. UIKit was specifically created for Apple's mobile devices though so is not available to developers who may want to port the same app to Mac OS X where user interfaces are created using AppKit. At least as far as the GUI is concerned, developers have been forced to write their own code.
The developers at The Iconfactory have created Chameleon to solve that problem. It is, they say, a clean room implementation of about 60 per cent of the functionality of UIKit. That is enough that many applications will need few changes in order to compile for the Mac. The Iconfactory's own Twitterrific Twitter client was actually ported to the Mac desktop using Chameleon and with the toolkit being developed in parallel. The program is available in the Mac App Store. This fact implies that the port is clean; some time ago Apple expanded its automatic checks to quickly determine if dis-allowed function calls were used in submissions and reject applications containing them.
However, it cannot be assumed that there is now a full portability between apps on iOS and Mac OS X. For example, there is still much missing from UIKit, notably the UISwitch and UITabBar components, Voiceover accessibility support and incomplete implementations of UITableView's editing. Apple requires that apps in the Mac App Store demonstrate full compliance by applications to Mac OS X interface guidelines so Chameleon ported applications will need to do more than just behave like an iOS app.
The source code of the project is available on GitHub, under the terms of the New BSD licence. The Iconfactory development still has a way to go, and in order to help finance this they are inviting interested parties to donate: for $250 you get a T-shirt with the project logo, for $500 a limited edition T-shirt and a set of 262 royalty-free icons from Iconfactory's Stockicons.com. The fund-raising drive ends on April 20th.