Eon's swift blog

Local spm dep

Aug 6, 2021
2 minute read

My notes on using local SPM packages

Pro:

  • Instant updates / faster builds (iterate faster) ✨
  • Keep modules in packages (encapsulation of code) ✨
  • Less remote downloads and network congestion and waiting times ✨
  • Keep a tree of packages and make them relative to each other
  • Keep many cross platform projects in the root folder. And reuse code in the hirarchy
  • You can still have spm tests in sub deps (and probably github actions if you wire it correctly)
  • Updates to asset files in packages
  • Repos don’t share code with each other explicitly (isolation) packages as well

Con:

  • Must be version controlled in the main proj
  • Bigger main git repo 👈
  • Relative paths can be a bit of chore to manage over time
  • More internal dependencies means less opportunity to easily add github actions CI tests and flags to deps
  • Over time, sub xcode projects needs to have their files readded etc
  • XCode renaming of instances sometimes gets to eager

XCode

  1. Make an SPM package
  2. Move the package into an xCode proj root folder
  3. Drag the package into xCode proj in xCode
  4. xCode - target - general - embed libraries and framework. click + and add package
  5. You can now import code from package in your main proj

Gotchas:

  • If a package can be used in other projects then keep the repo remote and standalone
  • If a package should have CI and github actions etc. Then keep the repo remote and standalone
  • If a package just need to be in its own namespace, and is built only for one project. then keep it as a local dependency repo inside main project folder
  • if a package requires frequent updates. it might be best to use local dep
  • if a change isn’t reflected in dependant repos -> right click on package and press update package
  • xCode search becomes available across all submodules when using such an umbrella structure 👌

Umbrella structure:

  • MainProject xCode workspace
    • package.swift (spm tests etc)
    • App ios (src code for ios app)
    • App macOS (src code for mac app)
    • packages/
      • iOS/ (packages for macOS)
      • mac/ (packages for iOS)
      • shared/ (packages for iOS and macOS)

Package

  1. Keep the package in the root of the proj
  2. Add to dependencies: .package(path: "CalculatorCore"), In the Package.swift
  3. Add to target dependencies: "CalculatorCore" In the Package.swift

Resources:

  • https://developer.apple.com/documentation/swift_packages/organizing_your_code_with_local_packages
  • https://developer.apple.com/documentation/swift_packages/developing_a_swift_package_in_tandem_with_an_app

Using submodules to mix remote and local packages

It’s also possible to do a hybrid local/remote system by using submodules in the main project. This way xcode doesnt have to download and build projects again and again. You can update the submodule repos, and even work in them and make changes.