Circle of Zen

Circle of Zen brings the japanese ritual "Enso" to your iPhone. It challenges you to draw a perfect circle by hand. One breath, one stroke. Find perfection in imperfection - with Circle of Zen.

Comment

Inspiration

Drawing an Enso—a one-breath, one-stroke circle in Zen calligraphy—teaches “perfection in imperfection.” I wanted a tiny daily ritual on iPhone that trains focus like a micro-meditation, but with instant, objective feedback that keeps it fun and shareable.

What it does

Circle of Zen challenges you to draw a perfect circle, equilateral triangle, or square in one stroke. You get an accuracy score and a heat-map outline showing where you drifted.

  • Best tries are saved and can be shared with friends.
  • Achievements reward streaks and milestones.
  • Free Enso background notes explain the ritual and its meaning.
  • Pro unlocks an exclusive training mode and unlimited tries. Purchases & restore are handled via RevenueCat.

How I built it

  • iOS (SwiftUI) for the UI and silky 120 Hz drawing.
  • Custom geometry analysis: resampling the stroke path, fitting to ideal shapes, angle/deviation checks, and a visual error overlay.
  • StoreKit + RevenueCat SDK for paywall, entitlement checks, and restore flow.
  • Lightweight local persistence for best attempts, achievements, and practice history.

Challenges I ran into

  • Getting drawing to feel natural while capturing precise vectors (touch noise, smoothing vs. latency).
  • Designing a scoring model that feels fair across different finger sizes and drawing speeds.
  • A paywall that’s clear and respectful (restore visible, short copy) and passes review smoothly.

Accomplishments that I'm proud of

  • A 30-second ritual users can do anywhere that genuinely builds focus.
  • Instant, interpretable feedback (heat-map + score) that motivates repeat tries.
  • Clean RevenueCat integration with reliable purchase/restore and minimal code.

What I learned

  • I used this challenge to learn Swift and Xcode. Before this, I had always used Python for my research projects (I’m currently pursuing a PhD in mathematics).
  • I learned how to plan and ship an iPhone app—from the first idea to publishing in the App Store.

What’s next for Circle of Zen

  • Drawing shapes is only the first step. I want to build a full Japanese meditation app around the Enso ritual, adding breathwork, calming soundscapes, and daily meditation sessions that strengthen focus through the practice of drawing perfect shapes.

Built With

Share this project:

Updates