johennes / swiftchallenge

A collection of coding exercises in Swift

SwiftChallenge

This is a collection of Swift coding exercises meant to be used for training and interviewing. Each challenge is contained in its own Swift package and includes a README with the problem statement and further instructions. There are code skeletons and unit tests in every package that help you to verify your solution.

An Xcode workspace is included for convenience. Since all code is contained in plain dependency-less Swift packages though, everything can be built, run and tested on both macOS and Linux.

Check out the index of challenges below or simply browse the folders in the repository.

Most of all, have fun and let me know about ideas for further challenges to be added. Currently unimplemented ideas are tracked in IDEAS.md.

Challenges by Category

Combinatorics

• Train Connections

Concurrency

• Synchronous Dispatch

JSON

• Date Decoding
• Heterogeneous Date Decoding
• Lenient Array Decoding

Other

• Meeting Overlap

Protocols & Subclasses

• Protocol Dispatch

Strings

• Anagram
• Auto Correction
• Reverse
• Reverse Polish Notation
• Version Sort

Challenges by Difficulty

Easy

• Anagram
• Date Decoding
• Reverse

Medium

• Auto Correction
• Heterogeneous Date Decoding
• Lenient Array Decoding
• Meeting Overlap
• Protocol Dispatch
• Reverse Polish Notation
• Synchronous Dispatch
• Version Sort

Hard

• Train Connections

Contributing

Want to contribute? Great!

Git(?=$|Hub|Lab)

The git setup is a bit unusual in that I'm self-hosting the main repository with mirrors on GitHub and GitLab. You cannot engage on the main repository directly because that would require me to set up a user account for you on my self-hosted instance first. However, you can open issues or pull / merge requests on one of the mirrors and I'll sync things with the main repository. If you're old-school, you can also just send me patches via email. 😄

Creating a New Challenge

Create the Package

To create a package for a new challenge, run the scaffolding script, e.g.

./scaffold Strings/WarpSort

Add the Package to the Workspace

Once you have the package, add it to the workspace. Since Xcode tends to mess up groups and paths, this step is best done by manually editing SwiftChallenge.xcworkspace/contents.xcworkspacedata.

Update the Schemes

Add a dedicated shared scheme for building and testing your package. Also add the tests in the All scheme.

Flesh out the Package Contents

Every package should contain a problem statement in its README, at least one documented solution and a battery of unit tests for verification.

Normalise Markdown and Regenerate the Main README

We use pandoc to enforce a consistent markdown format across the project. Run the normalize-markdown script to reformat all READMEs. Afterwards regenerate the main README by running the regenerate-readme script. This will automatically list your new package.

License

SwiftChallenge is licensed under the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.