// Senior iOS developer @ Trainline

I write Swift and build apps that nag you (politely).

I'm Petter, a senior iOS developer at Trainline. I led our move to iOS 26 and Liquid Glass, which we launched in partnership with Apple. Evenings and weekends, I build my own apps in Swift.

View my apps →
Swift Objective-C SwiftUI UIKit Combine Async/Await SPM Clean Architecture
Petter.swift 
struct Developer {
  let name = "Petter Vang Brakalsvalet"
  let role = "Senior iOS Developer"
  let company = "Trainline"
  let origin = "Hardware Tech"
  let learning = true // always
  let apps = ["reHydrate", "GuestLens"]
}▍
01 — apps

Things I've shipped

GuestLens app icon GuestLens app icon

GuestLens

app store

Your guests take better photos of your party than you do. GuestLens puts them all in one gallery. Out now on the App Store.

SwiftSwiftUIAsync/Await
Learn more →
reHydrate app icon

reHydrate

open source

A simple water tracker built to (gently) annoy you into drinking enough water. Live on the App Store.

SwiftUINotificationsHealthKit
Learn more →
View all apps →
02 — about

From circuit boards to Swift

I didn't start in software. My first job was fixing hardware at InfoCare in Norway: a PC one day, someone's watch the next. Seven years of that teaches you to work a problem backwards.

Then a BSc in Computer Science at Aberystwyth University in Wales, which is where I found iOS. reHydrate went on the App Store while I was still learning. After that I led iOS at Sonin App Development. These days I work on the Trainline app, which millions of travellers across the UK and Europe use.

~/now
buildingGuestLens 📸
working atTrainline
learningSwift Concurrency
based inUnited Kingdom 🇬🇧
03 — posts

Half-formed thoughts about Swift and about shipping things after hours.

· 4 min read

I built an app for my fiancée. Then I couldn't stop rewriting it

My first iOS app shipped in December 2020 with every function copy-pasted across screens. Three rewrites later it runs on an Engine-Presenter-Model-View architecture — and the Swift 6 migration has handed me a testing problem I still can't solve.

SwiftArchitectureSwift 6Testing
Read it →
All posts →
04 — work

Experience

git log --author=petter
commit 7f3a91c (HEAD -> main)
Date: 2023 — present
iOS Software Engineer · Trainline (Senior 2024–, Mid 2023–24)
I own our CI/CD and release infrastructure. Led the iOS 26 and Liquid Glass adoption with Apple. Wrote the Bodyless and Headless test frameworks, plus a regression-bisect tool that hunts down the commit that broke a test. PRs get their feedback 20 minutes sooner than they used to.
commit b2c8e40
Date: 2021 — 2023
Tech Lead iOS · Sonin App Development (Tech Lead 2022–23, Junior 2021–22)
Lead developer across the iOS portfolio. Designed the feature-based modular architecture the team settled on, and set our tooling standards. Mentored developers up to "Project Champion".
commit a1d5f02
Date: 2013 — 2020
Computer Technician · InfoCare (Norway)
Diagnosed and repaired PCs, tablets, phones and watches, in three languages.
05 — contact

Say hello.

Got a role to fill, or a project you want a second opinion on? Email me. I read everything and answer most of it.

Email me → GitHub LinkedIn App Store