This looks like an interesting opportunity to work with a remote API as well as tinker with the UI:
Open Source Weather App created with Swift
Question: Is it vital to understand the concept of Monads to program in Swift? Answer: No.
Al explores concepts relating Monad and Swift based on talks at Swift London Meetup and Swift Summit.
Justin Spahr-Summers walks through the why, what and how of Carthage:
Carthage is a new dependency manager for Objective-C and Swift projects, intended to be the simplest way to add frameworks to a Cocoa application. Carthage works by delegating tasks to Xcode and Git, minimizing new concepts as much as possible, so you can continue to use the tools you’re already familiar with.
Ruthlessly Simple Dependency Management
BKAsciiImage was written by Barış Koç to convert UIImage objects to ASCII art. Conversion can be done in the background via completion block and can also be output as an NSString.
Although there may be a specific use case for converting an image to ASCII, it escapes me at the moment. However, I do find the idea intriguing.