问题
I am trying to understand how the compatibility does work and could not get the perfect answer out there. Many answers are confusing.
I want to understand if I develop an app targeting iOS 9, does it work on iOS 11.2 devices for example (forward compatibility)
and if I target iOS 11.2, is it going to be compatible with iOS 9 and 10 as an example (backward compatibility)
I found this answer where he is suggesting to download the image file for an older versions. When shall I do that? What is the case that requires downloading the images to my project?
This issue is giving me the following error:
My iPhone is running iOS11.3 and my Xcode Project (Objective-c) is targeting iOS 10 and I am developing using Xcode 9.2
回答1:
- Apple only supports 'forward compatibility'. You can specify your App's min OS support in its target. All OS version higher than the min target version will support your app. You can't make your app to support OS versions less than the target version.
- This "Could not locate device support files" error occurs when your Xcode is not compatible with the OS version of the device. In such scenarios, you can download those image and make your Xcode compatible with the OS version.
- "When to download the images??" - When you can't update your Xcode to its newest version( for eg: if you are using Sierra and no plans to update to High Sierra).
来源：https://stackoverflow.com/questions/49615828/xcode-ios-backward-and-forward-compatibility-for-deployment-target