I built an offline-first iOS app in 43 days with Swift, SQLite, and Claude Code

My wife buys secondhand items at flea markets and car boot sales in the UK and resells them on eBay and Vinted. She was tracking everything in Google Sheets and kept forgetting what she paid for things. When someone sent an offer she had no idea if it was a good deal. So I built her an iOS app. That was 43 days ago. It's now on the App Store, completely free, and a few people are actually using it. Here's how I built it and the technical decisions along the way. What the app does You take a photo at the market, enter the price, and the app tracks the item through its lifecycle: purchased → listed on platforms → sold. It calculates profit after all expenses — entry fees, transport, packaging. Supports 4 currencies with automatic exchange rates. Works completely offline. Tech stack Swift + SwiftUI — iOS 17+ SQLite via GRDB — local storage with WAL mode, foreign keys, composite indexes Google Drive API — optional photo sync + CSV export (drive.file scope only) BGTaskScheduler — background