I highly recommend that you talk to an iOS app developer if you have any doubts about whether your app will run on iOS 7. A basic consult with a reputable developer may cost you nothing and save you from an embarrassing app problem.
But if you want to self-diagnose your app, here is some key information about how the iOS 7 update affects iOS app development.
The New Navigation Systems
The bad news: your old menu navigation system will look, well, old.
Having an old-style navigation system probably wonâ€™t be a problem for a few weeks or months after iOS 7 gets officially released, but as more and more business use iOS app development to upgrade their apps, your app will look older and less well-maintained.
Itâ€™s quite likely that six months after the release of iOS 7, users wonâ€™t take seriously any app which uses old-style menus.
Retina Displays Only
Apple has announced that iOS 7 will be available for Retina displays only. Users of pre-Retina versions of the iPhone wonâ€™t be able to upgrade.
At first, this may not seem to affect your appâ€”if it works on older devices now, it will continue to work. But you will need to be careful once you start upgrading your app for iOS 7 devicesâ€”many new features will only be available on iOS 7.
The new menu system, for example, wonâ€™t work on older devices, so youâ€™ll need to maintain two separate menus. (This should be relatively simple for most apps if your iOS app developer uses a good design tool.)
Once again, the good news is that your current launcher icon will work automatically on iOS 7, with it retaining its existing appearance or being automatically adapted by iOS 7â€”but itâ€™ll also look increasingly out of place among icons designed natively for iOS 7.
Other icons your software provides may not be so lucky. As iOS 7â€™s new color scheme and layered display depends on certain icon features, your icon could be automatically adjusted in ways contrary to good appearance. For example, an already partially-transparent icon could disappear when made more transparent under a layer. Or an icon which matches the background color without providing the necessary hinting to iOS 7 could lose its distinct border.
Also, the few apps which have not already provided Retina-quality icons will find their icons dynamically rescaled by iOS 7, possibly creating image artifacts.
As with menus, creating new icons for most apps should not require much new graphic design work, but you will need to maintain separate icon profiles for non-Retina devices, pre-7 devices, and iOS 7 devices.
Apple is shipping iOS 7 with a bunch of new Application Programming Interfaces (APIs) which allow apps to better integrate with iOS 7 and Safari. Although these new APIs shouldnâ€™t affect older apps, programmers know that any major API change can break compatibility with existing APIs. This is especially true of undocumented APIs from iOS 6.1.
With Apple using the new APIs in-house for its own apps, itâ€™s possible that bugs have crept into the existing APIs, so Apple recommends that you fully test your existing app on iOS 7 to ensure that it works correctly.