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?
No )-:
This topic in more complex than it might seem. In most cases a change applies to the OS release where the change was made, and then to future OS releases after that. However, there are some exceptions:
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If a change might cause significant compatibility problems, Apple can guard it with an SDK check (a linked-on-or-later check). That is, the OS only enables the change if the current program was built with a new SDK.
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Some changes can back deploy. That is, once you build with the new tools then the change applies to all OS releases on which your app runs.
Usually the releases notes call out such exceptions, but that’s not universally true.
If you have questions about specific changes, feel free to add them here and I’ll take a look.
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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"