AI_Implementation.md

How This App Was Architected & Built

This project was developed following strict senior-level iOS engineering standards, with guidance from an AI assistant (Grok) acting as a Senior iOS Engineer specializing in SwiftUI and modern Apple frameworks.

Guiding Principles (from AGENTS.md)

Protocol-Oriented Programming (POP) first: All shared capabilities defined via protocols before concrete types
MVVM-lite: Views are "dumb" — all logic lives in @Observable view models
No third-party dependencies: Pure Apple frameworks only (SwiftUI, AVFoundation, StoreKit 2, CoreImage)
No magic numbers: All dimensions, opacities, durations from centralized Design constants
Full accessibility: Dynamic Type, VoiceOver labels/hints/traits/announcements
Modern Swift & SwiftUI: Swift 6 concurrency, @MainActor, foregroundStyle, clipShape(.rect), NavigationStack
Testable & reusable design: Protocols enable mocking and future SPM package extraction

Architecture Overview

Shared/ ├── DesignConstants.swift → Semantic design tokens (spacing, radii, sizes, etc.) ├── Color+Extensions.swift → Ring light color presets ├── Protocols/ │ ├── RingLightConfigurable.swift → Border, color, brightness, mirror, smoothing │ ├── CaptureControlling.swift → Timer, grid, zoom, capture mode │ └── PremiumManaging.swift → Subscription state & purchase handling └── Premium/ └── PremiumManager.swift → Native StoreKit 2 implementation Features/ ├── Camera/ → Main UI, preview, capture logic ├── Settings/ → Configuration screens └── Paywall/ → Pro subscription flow

Key Implementation Decisions

Ring Light Effect
- Achieved by coloring the safe area background and leaving a centered rectangular window for camera preview
- Border width controlled via user setting
- Gradient support added for directional "portrait lighting"
Camera System
- AVCaptureSession with front camera default
- UIViewRepresentable wrapper for preview with pinch-to-zoom
- Video data output delegate for future real-time filters (skin smoothing placeholder)
Capture Enhancements
- Timer with async countdown and accessibility announcements
- Volume button observation via KVO on AVAudioSession.outputVolume
- Flash burst: temporarily sets brightness to 1.0 on capture
Freemium Model
- Built with pure StoreKit 2 (no RevenueCat)
- PremiumManaging protocol enables easy testing/mocking
- Clean paywall with benefit list and native purchase flow
Reusability Focus
- All shared logic extracted to protocols
- Ready for future extraction into SPM packages:
  - SelfieCameraKit
  - SelfieRingLightKit
  - SelfiePremiumKit

Development Process

Iterative feature additions guided by competitive analysis of top App Store selfie apps
Each new capability (timer, boomerang, gradient, subscriptions) added with protocol-first design
Strict adherence to no magic numbers, full accessibility, and clean separation
Final structure optimized for maintainability and future library extraction

This app demonstrates production-quality SwiftUI architecture while delivering a delightful, competitive user experience.

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