The current version of Vienna requires Xcode 7 and Mac OS X 10.11 SDK. We will be officially moving to Xcode 8 and macOS Sierra SDK once it has been released. Currently the Unit Tests require Xcode 8 and Swift 3.
Vienna uses cocoapods for managing dependencies. When building, make sure to always open the Xcode workspace Viennna.xcworkspace instead of a project file.
You should have a basic knowledge of Git and read this advice on workflow.
As a starting point, search for any issues with the help-wanted label.
Please let us know what you are working on by posting an issue on Vienna's github and assigning it to yourself.
For Objective-C code, please try to follow the Spotify Objective-C Coding Style.
For Swift code, please try to follow the GitHub Swift Style Guide.