Develop a Mac Application

I currently have a swift prototype that I have connected to a Firebase database. I need a developer that can make the UI for a Mac app. I would like something that look similar to the Spotify app. I can handle the backend of the app. Develop will need to know how to use Github. Example projects will be helpful in deciding winner. UI will need to be compatible with existing swift code base. Mac app will have chatting functionality, Facebook, twitter and Instagram sharing capability.