iOS 7′s new look is a major departure from every other version of iOS. Every single application currently on the App Store has been designed for those past versions of iOS, so it’s likely that developers and designers alike are going to want to update their applications to take full advantage of the latest design cues.
Apple has already posted a guide online that is aimed at making the transition painless, if not easy. The guide highlights best practices, discusses the thought that went in to the iOS 7 design, and brings up the issue of supporting iOS 6 and its pre-iOS 7 design language.
First off, it appears that many of the iOS 7 changes will be applied to apps just by building the application in the latest version of XCode. However, unless your app is incredibly basic and was designed completely in Apple’s XCode environment with little to no outside input, there will be some amount of work involved in making it look native:
Custom apps—that is, apps that use no UIKit UI elements—require a more nuanced approach. For example, if you feel that the current UI and experience of the app is still appropriate, there may be very little to do. On the other hand, if you feel that the app’s personality and user experience should change in order to delight iOS 7 users, you have more work to do.
The guide is an excellent read, even for non-developers: it provides insight in to just how much has changed in terms of design with iOS 7, and gives an appreciation for the work that will soon be put in to every app in the App Store. For developers, this guide may well become something of a lifeline over the next year or so.
Note: the guide may ask for login information, as it is on Apple’s developer site. However, I was able to get in without actually being a developer; I simply logged in with my typical Apple credentials. Mileage may vary.