NightGuard: Sleep & Habits

2025 Updates: Verified 50+ downloads. Focus on Sleep Hygiene.ctive users.

NightGuard is a native iOS application engineered to help users reconstruct their sleep hygiene through data-driven habit formation. Unlike passive trackers, it actively intervenes in the pre-sleep routine using a “Guard” mechanism.

🛠 Technical Stack

• Language: Swift 5.9
• UI Framework: SwiftUI (100% coverage)
• Data Persistence: Core Data + CloudKit (Sync)
• Hardware Integration: HealthKit (Read/Write Sleep Analysis), Haptics
• Architecture: MVVM-C (Model-View-ViewModel-Coordinator)

💡 Key Features & Engineering Challenges

1. HealthKit Integration & Privacy

The app communicates directly with the Apple Health data store.

• Challenge: Handling granular sleep stages (REM, Deep, Core) and presenting them effectively.
• Solution: Implemented a custom query pipeline that aggregates HKCategorySample data into visualized “Sleep Sessions”.
• Privacy: Zero-knowledge architecture. All health computations happen on-device (Edge Computing principle).

2. The “Guard” Mode (Focus State)

An immersive mode that prevents phone usage before bed.

• Implementation: Utilizes DeviceActivity framework (Screen Time API) to discourage app usage during the “Wind Down” window.
• UI/UX: Extensive use of SwiftUI Animations and MatchedGeometryEffect to create a fluid, calming transition into sleep mode.

3. Data Visualization

• Custom charts built with Swift Charts to correlate “Habit Completion Rate” with “Sleep Quality Score”.
• Provides actionable insights (e.g., “You sleep 20 minutes longer when you read before bed”).

🚀 Impact

• 50+ Downloads on the App Store.
• 5.0 Star Rating on the App Store.
• Selected as a showcase project for the school’s CS fair.