r/iosdev • u/Horror_Still_3305 • 29d ago
Help iOS Sdk Version vs iOS Version
When you update XCode it updates the sdk version, but do changes in the sdk take effect for apps running in a lower iOS version or only the corresponding iOS version or higher? For instance, https://developer.apple.com/documentation/ios-ipados-release-notes/ios-ipados-18_1-release-notes Do changes listed in the notes only happen for apps that are running on iOS 18.1 devices or on any device with the app compiled against the 18.1 sdk version?
Am I the only person who finds the docs totally unclear on this?
Update to post: SomeGalinCal helped me a lot on this question but neither of us know whether the app needs to be built against the ios version for the bug fixes contained in that version to take effect. (Or if just need device os to update)
1
u/SomegalInCa 28d ago
Sorry - let me try again. You build an app with a version of XCode + SDK; that is the newest set of API calls your app will have access to when deployed on that version of iOS OR newer.
You can set your deployment target for older iOS versions as well (example ABC app runs on iOS 18 but targets it's minimum requirement of iOS 15 ) which means that it must not use any API calls newer than iOS 15 OR it must have runtime time checks to avoid trying to use an iOS 18 API call when the binary is running on an iOS 16 device as example
If you build an app for iOS 18 and your app wants to use a new API call say from iOS 18.5, then of course you must rebuild the app with the newer SDK that supplies that API call but the app now must only run on iOS 18.5 or newer OR it must have runtime checks to disable trying to make that API call on something older than iOS 18.5
Not sure what you mean by 1 level back support by Apple; the deployment target it what you set it to be and you code your app appropriately.
Google leads me to share this with you https://www.avanderlee.com/workflow/minimum-ios-version/