iOS Developer — Emotional Wellness Audio App (Prototype & Spec Finalized, Ready to Build)

We’re Big Hug Studios, building Big Dad Hug - an iOS app that delivers short, professionally recorded “Dad talks” (warm, fatherly audio messages) across 8 life categories, with sentence-by-sentence text highlighting during playback. The design phase is done: every screen, flow, state, and copy string is finalized in a working React/JSX prototype you can click through. We need a developer to turn it into a production iOS app - no design work involved. Scope includes the full app (onboarding, audio playback with highlight sync, voice selection, mood tracking), subscriptions via RevenueCat (free tier + monthly + annual), a lightweight backend for mood history and milestone triggers, push notifications, and App Store submission. Audio is professionally recorded and delivered as named WAV files; we’re planning Cloudflare R2 for delivery but open to your recommendation. One open question we want your take on: native Swift/SwiftUI vs. React Native - the app is iOS-only at launch, but a sibling product on the same architecture is likely later. We work in fixed-price milestones (escrowed through Upwork), roughly: (1) core app shell - onboarding, Home, Category, and Playback with simulated audio; (2) subscriptions + backend; (3) real-audio sync, polish, and App Store submission. The first milestone is deliberately small so we can confirm fit on both sides before scaling up. To apply, please include: (1) a link to at least one app you’ve shipped that’s live on the App Store, ideally with audio playback, subscriptions, or a content catalog (2) your answer to this question - how would you sync sentence-by-sentence text highlighting to audio playback, and what are the gotchas? (3) your recommended stack and why (4) your rough timeline. Serious applicants get the full technical brief plus the prototype file to scope from. Clear, responsive written communication matters a lot to us - we’d rather answer ten questions up front than discover assumptions later.