This is a proposal for a new standard for the iOS community: a text-based file that defines the Xcode version to use to compile and package a given iOS project.
This will be used by this gem, however it's designed in a way that any tool in the future can pick it up, no matter if it's Ruby based, Swift, JavaScript, etc.
Similar to the .ruby-version file, the .xcode-version file allows any CI system or IDE to automatically install and switch to the Xcode version needed for a given project to successfully compile your project.
The filename must always be .xcode-version.
The file must be located in the same directory as your Xcode project/workspace, and you should add it to your versioning system (e.g. git).
The file content must be a simple string in a text file. The file may or may not end with an empty new line, this gem is responsible for stripping out the trailing \n (if used).
To define an official Xcode release
9.3
7.2.1
You can also use pre-releases
11.5 GM Seed
12 beta 6
Always following the same version naming listed by xcversion list.
Note: Be aware that pre-releases might be eventually taken down from Apple's servers, meaning that it won't allow you to have fully reproducible builds as you won't be able to download the Xcode release once it's gone.
It is recommended to only use non-beta releases in an .xcode-version file to have fully reproducible builds that you'll be able to run in a few years also.