Amortized (EZ-Payment-Calc)

iOS app for calculating amortized loan payments and viewing current U.S. mortgage rates from the St. Louis Fed (FRED) API.

Bundle ID: com.groundspeedhq.Pay-Calc
Requirements: Xcode, iOS 18.6+ (Simulator or device)
Stack: Swift 5, SwiftUI, MVVM

Features

• Payment — Loan amount, down payment, interest rate, and term; computes monthly payment with optional speech output.
• Rates — Live 30-year fixed, 15-year fixed, and 5/1 ARM rates from FRED (today vs. last week).

Build & Run

From the repo root:

# Build
xcodebuild -project Amortized.xcodeproj -scheme Amortized -configuration Debug -sdk iphonesimulator build

Or open Amortized.xcodeproj in Xcode and run on a simulator (recommended).

Tests

# List simulator IDs
xcodebuild -showdestinations

# Run all tests (replace <UUID> with a simulator ID)
xcodebuild -project Amortized.xcodeproj -scheme Amortized -destination 'platform=iOS Simulator,id=<UUID>' test

# Run a single test class
xcodebuild -project Amortized.xcodeproj -scheme Amortized -destination 'platform=iOS Simulator,id=<UUID>' -only-testing:AmortizedTests/ClassName test

Tests cover PaymentService (PMT calculations), FRED JSON decoding, and view models.

Architecture

• Entry: AmortizedApp.swift — SwiftUI App with a TabView (Payment + Rates).
• UI: SwiftUI views (PaymentView, RatesView) and ObservableObject view models.
• Logic: PaymentService for amortization math; ApiService for FRED (30yr, 15yr, 5/1 ARM).

Rates use FRED series: MORTGAGE30US, MORTGAGE15US, MORTGAGE5US. A FRED API key is required (configured in ApiService).