A quiz adventure across 17 floating worlds of real, syntax-highlighted Swift — 250+ bite-sized levels, from let to async/await.
Free. No ads, no in-app purchases · iOS 26+ · iPhone & iPad
How it works
17 worlds, 250+ levels of bite-sized Swift. Start at Swift Basics and unlock your way to Performance.
Four question types built on real, syntax-highlighted Swift. A run takes minutes, not an evening.
Perfect runs earn three gold stars. Build a daily streak and climb the leagues.
Question types
Four bite-sized formats — because reading code is a skill of its own.
What does this code print?
let numbers = [1, 2, 3]
let doubled = numbers.map { $0 * 2 }
print(doubled)Half of programming is reading code someone else wrote. These questions train exactly that — you run the Swift in your head, then check yourself.
Which of these is a value type?
Quick checks on the ideas underneath the syntax — value semantics, ARC, protocols, concurrency. The stuff interviews are made of.
a || b, Swift skips evaluating b whenever a is true.Fast calls on statements that sound plausible either way. Great for shaking out half-remembered rules.
Complete the code.
1func loadProfile() async throws -> Profile {
2 let user = try await fetchUser()
3 return Profile(user: user)
4}Drop the missing keyword into real Swift. Muscle memory for syntax, without typing on glass.
The journey
From let to async/await — each world has 15 levels plus 5 Advanced challenges that unlock at 100%.
map transforms every element of a collection and returns a new array of the same length — it never drops elements.
numbers.map { $0 * 2 } // [2, 4, 6]If you want fewer elements, you're thinking of filter or compactMap.
No wrong answers wasted
Miss a question and Deep Rabbit opens a full explanation — paragraphs, inline code, the works. Then the run moves on.
Three hearts per run, back over time. Friendly, never punishing — and nothing to buy.
Deep Rabbit is free. No in-app purchases, no dark patterns. Sign in with Apple and play.
Habit, not homework
A daily flame, best-streak stats, accuracy, player level — and an achievements grid with a few mysteries left in it.
Open content
Every question in Deep Rabbit lives in a public GitHub repo. Spotted a mistake, or think the game needs a whole new section? Open a pull request — merged content ships to everyone.
Free on iPhone and iPad. No ads, no in-app purchases — just Swift.
Join the TestFlight beta// Go deep. Take your time. Happy hacking.