Semantic versioning in Swift
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CommonTests Merge pull request #2 from neilpa/replace-llamakit Jun 16, 2015
SemverKit-OSXTests Tests and fixes normalized option parsing. Sep 24, 2014

SemverKit — Semantic Versioning in Swift

SemverKit is a pure Swift implementation of the Semantic Versioning 2.0 specification. It includes a parser for version strings, as well as comparison and equality operators. As an extension, it also includes semantics for incrementing versions, with special support for alpha and beta pre-release versions.

SemverKit exists for both iOS and OS X, with the OS X version having an eye towards being useful for the creation of scripts and command-line tools. The OS X framework therefore includes additional functionality, such as consistent parsing of options.

Basic Usage

The first point of contact with the API is likely going to be the parser.

let result1 = parseVersion("2.0.1-alpha.2") // { Success 2.0.1-alpha.2 }
let result2 = parseVersion("a.0.2-alpha.3") // { Failure String "a.0.2" could not be
                                            //   parsed as a number in normal version: "a.0.2" }

The parser returns a Result type, an enum that is either a Success or a Failure, depending on whether or not the parsing was successful. Upon failure, a message describes the source of the error. A successful parse contains the core type of the library: a Version.

Version is Equatable and Comparable, fully implementing the semantics of the spec:

 2.0.1 < 2.0.2 < 2.1.0 < 2.2.0 < 3.0.0 < 3.1.0-alpha.0 < 3.1.0-alpha.3 < 3.1.0-beta < 3.1.0-beta.0 < 3.1.0-beta.1 < 3.1.0-lexically-larger < 3.1.0

Of course, version metadata is fully supported, but ignored during equality and comparison operations.


In addition to supporting basic comparison of versions, SemverKit also includes support for incrementing versions in a consistent manner. A number of methods are defined to support:

  • Incrementing normal versions (patch, minor, major)
  • Incrementing pre-release versions (to pre-release alpha and beta versions and to normal versions)
  • Stabilizing a version

All these methods are prefixed with next*, and their return values are uniquely defined. For instance, nextMajorAlphaVersion defines what it returns as:

The next major alpha version of version v1 is defined as the smallest version v2 > v1 with:

  • A patch number of 0
  • A minor number of 0
  • A pre-release of alpha.X, where X is an integer

This allows for precise semantics, which makes SemverKit suitable for automated versioning.


Minimum system requirements:

  • Xcode 6.3 β4
  • OS X Mavericks 10.10


  1. Clone this github repository, and build the project.
  2. Run the tests, just for sanity. They should all pass.
  3. Copy SemverKit.framework from the DerivedData directoy to /Library/Frameworks (this will require sudo access)

SemverKit should now be available for use from a command line script. The shebang needs to read:

#!/usr/bin/env xcrun swift -F /Library/Frameworks

This is because the Swift compiler, unlike Clang, doesn't automatically pick up frameworks in /Library/Frameworks.

Including SemverKit in Other Libraries

Use Carthage. SemverKit, of course, uses semantic versioning, so the corresponding Cartfile line should be:

github "nomothetis/SemverKit" == 0.2.0