Vocapy Language Learning

During our user research at Apple Developer Academy, we discovered something interesting: most language learners struggle with vocabulary retention, but it's not because they don't try hard enough. The problem with existing flashcard apps: • They're designed for fast learners (overwhelming for slow-paced learners) • They're too gamified (turns learning into a stressful competition) • They don't respect the natural forgetting curve • They're cluttered with features that distract from actual learning We interviewed 50+ language learners and found a consistent pattern: people wanted a simple, distraction-free app that would help them learn at their own pace without pressure.

As the Tech Lead, I researched various spaced repetition algorithms and decided on the Leitner system - a proven method that's been used since the 1970s. The implementation: 1. Words start in Box 1 (review daily) 2. Correct answers move words to the next box (longer intervals) 3. Incorrect answers send words back to Box 1 4. Each box has optimal review intervals based on memory research I built this using SwiftData for local storage and CloudKit for sync across devices. The architecture was Clean Architecture with MVVM, separating: • Domain layer (business logic, Leitner algorithm) • Data layer (SwiftData, CloudKit) • Presentation layer (SwiftUI views) This separation made it easy to test the spaced repetition logic independently from the UI.

Working with our UI/UX designer, we decided on a radical approach: remove everything that's not essential for learning. No leaderboards. No streaks that make you feel guilty. No XP points. Just you and your vocabulary. The core flows we focused on: • Adding words (should take <30 seconds) • Reviewing words (minimal friction, maximum focus) • Tracking progress (motivating, not stressful) For the review interface, we used large, readable typography with ample whitespace. The SwiftUI animations were subtle - just enough to provide feedback without being distracting. One interesting technical challenge: implementing smooth swipe gestures that felt natural while preventing accidental inputs. I used SwiftUI's DragGesture with careful threshold tuning.

After launching on TestFlight, the feedback was overwhelming. One user wrote: "This is the first vocabulary app that doesn't make me feel like I'm failing." The metrics showed: • 85% retention rate (users still active after 1 month) • 60% daily active users • Average of 100+ words learned per user • Positive reviews highlighting the "distraction-free" design But the most rewarding moment? When a user messaged us saying they finally passed their language exam after struggling for months with other apps. That's when I realized - sometimes the best technology is the one that gets out of your way and lets you focus on what matters.