iOS4 Compatibility for iPhone App

Question

I want to upgrade my iPhone app from iOS3 to iOS4.

Once I upgrade to iOS4, which versions of previous iOS does the app support? For eg. will it support iOS3, iOS2, etc.

Thanks!

Answer 1

It will depend on what features you implement. If you implement a feature that is specific to iOS 4 (like in-app sms), then that feature will not run on previous versions. In some cases this may cause you app to not function on old versions. Make sure the feature is available at runtime before you try to use it.

In your target's build settings there is 'Base SDK' and 'Deployment Target'. 'Base SDK' is the newest iOS that you want to compile for, while 'Deployment Target' is the oldest iOS that you want your app to function on.

Answer 2

You can set the Deployment Target of your application to the base version of the SDK that you want your app to be compatible with. Once set, your app will be compatible with all versions of the SDK from the deployment target through the current version.

Answer 3

The iOS 4 SDK can build an app that'll run on iOS 3.0—by setting the project's Deployment Target to same—but no earlier. On the other hand, just about nobody is still running 2.x, so that limitation isn't likely to be a problem.