Conversion

Easy Unit

A polished Apple-native unit conversion app for iPhone and iPad, built with SwiftUI + MVVM.

Phase 1 features

• Friendly home converter with one focused conversion surface
• Dedicated Units tab with search and category sections
• Dedicated Toolkit tab for one-input, many-output conversion within a chosen category
• Favorite units shown at the top of the Units tab for quick switching
• Reversible conversion direction inline
• Favorite toggles available in the Units list
• Local persistence of favorites
• Last-session state restoration (tab, last used pair, search, per-pair swap direction)
• Converter input value is cleared when the app relaunches
• Instant conversion updates while typing
• Clean numeric output formatting capped at 3 fractional digits
• iOS/iPadOS Settings app entry shows dynamic app Version (Build)

Supported conversion pairs (reversible)

• cm <-> inches
• meters <-> centimeters
• kg <-> lbs
• kg <-> grams
• celsius <-> fahrenheit
• celsius <-> kelvin
• mm <-> inches
• meters <-> feet
• km <-> miles
• miles <-> feet
• cm <-> feet
• lb <-> grams
• grams <-> ounces
• inches <-> feet
• tsp <-> mL
• tbsp <-> mL
• liters <-> gallons
• pt <-> L
• qt <-> L
• pounds <-> ounces
• kph <-> mph (defaults to kph -> mph when opened)
• kph <-> m/s
• mph <-> m/s
• psi <-> bar
• psi <-> kPa
• bar <-> kPa
• acres <-> hectares
• acres <-> square feet
• square feet <-> square meters
• radians <-> degrees
• hp <-> kw
• meters <-> yards
• mL <-> cups
• fl oz <-> mL

Architecture

• ConversionCatalog is the single source of truth for supported converters.
• ConversionRule is backed by Foundation Measurement / Unit conversions.
• ConversionsViewModel handles selected pair, input, swap state, search, and output.
• ToolkitViewModel handles category/source-unit selection and multi-output conversion rows.
• FavoritesStore + FavoritesPersistenceService handle local favorites persistence.
• SessionStateStore restores tab/search state plus last-used pair and per-pair session state.

Build and test

Build:

xcodebuild -scheme Conversion -project Conversion.xcodeproj -destination 'generic/platform=iOS Simulator' build

Run unit tests:

xcodebuild -scheme Conversion -project Conversion.xcodeproj -configuration Debug -destination 'platform=iOS Simulator,name=iPhone 17' -only-testing:ConversionTests -skip-testing:ConversionUITests test

Project structure

Conversion/
├── Models/
├── Stores/
├── Utilities/
├── ViewModels/
├── Views/
├── ConversionApp.swift
└── ContentView.swift