prince-conversions

Air Fryer Converter

An iOS app that converts oven recipes to air-fryer time + temperature, lets you save recipes, and runs concurrent cook timers with a “shake halfway” reminder.

Built with Expo SDK 54 / React Native, intended to ship via EAS Build to TestFlight.

What’s in here

design/ — the original HTML / JSX prototype (Air Fryer Converter.html and the screen / device-frame mocks the prototype was built from). Useful as a visual reference for the warm cream + terracotta aesthetic.
app/ — the actual React Native app.

Features

Two-way conversion (oven ↔ air fryer) with °F / °C unit toggle, stepping in 5° increments. Hold the +/- buttons to auto-repeat with accelerating speed and per-tick haptics.
Saved recipes, persisted via AsyncStorage. Save sheet has a scrollable emoji picker, custom-emoji input, and notes.
Cook timer launched from the result card or by saving a recipe.
Multi-timer support: timers stack iOS-notification-style at the bottom, collapsed by default with a peek; tap to expand into a full list.
Full-page timer screen with an animated SVG progress ring, accurate even after backgrounding.
“Shake halfway” chime + haptic at the midpoint, toggleable per timer from the full-page view.
When a timer ends, it stays in the list and the chime loops every 2.6s until you cancel or restart it. Restart resets the same timer to its original duration.
Two distinct chime sounds (generated programmatically — see app/scripts/make-sounds.js): a warm major-arpeggio bell for “done” and two bright dings for “shake halfway”. Plays with the iOS silent switch on.
Animated splash: degree-mark bounces onto the F with squash-and-stretch.

Run locally

cd app
npx expo start

Press i to launch the iOS simulator.

Product analytics

The app sends a small set of anonymous, manually defined product events to PostHog when it is configured. Autocapture, session replay, and user-entered recipe content are excluded.

Create an EU-hosted project at https://eu.posthog.com.
Copy app/.env.example to app/.env.local.
Add the PostHog project token. This is a public client token, not a personal or secret API key.
Add the same EXPO_PUBLIC_POSTHOG_API_KEY and EXPO_PUBLIC_POSTHOG_HOST variables to the EAS production environment.
Enable impression-level ad revenue in AdMob if you want ad_revenue_recorded events in addition to ad impressions.

Analytics remains a no-op when no project token is configured and is disabled in development by default. Users can turn it off in Settings. Update the App Store privacy disclosure before releasing this version.

Timers in the background

Active timers are persisted (@afc/timers-v1) and their alerts are scheduled with the OS via expo-notifications (src/notifications.js), so a locked phone still gets the “shake halfway” and “done” alerts with the app’s own chimes. Notification permission is requested the first time a timer starts. In the foreground the system notification is silenced and the in-app chime / toast handles it. Timers that finished more than an hour ago are dropped on the next launch instead of ringing.

app.json declares the iOS time-sensitive entitlement and Android’s USE_EXACT_ALARM so alerts land on time; Play Console asks you to justify the latter (the app runs cook timers).

initAds() runs Google’s User Messaging Platform consent flow before initialising AdMob, then the ATT prompt on iOS. For the form to appear you must publish a GDPR message (and, optionally, a US states message) under AdMob → Privacy & messaging for this app; without one, EEA/UK users get no ads. Settings shows an “Ad privacy options” row only where the SDK says one is required.

Both platforms have real AdMob IDs wired in (app.json for the app IDs, src/ads.js for the banner units). The Android app is registered in AdMob but not yet linked to a Play listing, so it shows as “Requires review” and ad serving stays limited until the app is published to Play and approved. Development builds always serve Google’s test banner regardless.

Pro paywall + i18n

Dedicated Pro paywall (app/src/screens/PaywallSheet.js): opens from Settings → Remove ads, and at most once per app version as a soft prompt after three completed timers (never mid-cook). Copy lives in app/src/i18n/locales/en.json via i18n-js + expo-localization. Add de.json / es.json / … and register them in app/src/i18n/index.js to localize. Button price uses RevenueCat’s localized priceString.

src/review.js asks for an App Store / Play rating after three completed timers, once per app version, only while the app is in the foreground. The share button on the result card sends 425°F oven for 25 min → 400°F air fryer for 20 min with the App Store link.

Build for TestFlight

cd app
npx eas-cli login
npx eas-cli init                                  # one-time, populates extra.eas.projectId
npx eas-cli build --platform ios --profile production
# fill in submit.production.ios in eas.json (appleId, ascAppId, appleTeamId)
npx eas-cli submit --platform ios --latest

Regenerate assets

cd app
node scripts/make-icon.js     # icon.png, adaptive-icon.png, splash.png, favicon.png
node scripts/make-sounds.js   # done.wav, shake.wav