iOS Engineer since 2012

iOS Engineer
from Hamburg

From zero to App Store

I build native iOS apps that people actually use. I've successfully shipped multiple apps and contribute to open source. I have expertise in every step of the development cycle—from shaping the idea, prototyping, designs and mockups, UX and UI, through implementation and coding, to continuous integration, deployment, and App Store Connect setup. My focus is on clean code and solid architecture.

Design
Code
Tooling
Sebastian Boldt Portrait Placeholder

Core Skills

Swift & SwiftUI
Point-Free Ecosystem
Modular Architecture
UX and UI Design
Agentic Coding

What I Do

I build iOS apps with clean architecture, modular design, and code that's easy to maintain.

Architecture & Modularity

I work primarily with The Composable Architecture (TCA) and the Point-Free ecosystem to build apps that are testable and maintainable. I break apps into modular packages using Swift Package Manager, and I can also set up solid architectures using just SwiftUI and Swift when that's the right approach.

The Composable Architecture Modular Architecture White-Labeling

Framework Knowledge

I work daily with SwiftUI and have extensive experience with UIKit on large-scale projects. I can also work with Objective-C when needed for legacy codebases or integrations.

Swift SwiftUI Objective-C UIKit

Team Collaboration & Mentoring

I mentor developers and present on iOS topics. I've worked in large international teams with mono-repos and multi-repo setups, as well as smaller local teams—each has its own challenges and I adapt to what works best.

Large Team Collaboration CI/CD Management Release Automation

Agentic Coding

I work with AI coding tools like Claude Code, Cursor, and Codex to accelerate development—while using Skills, MCP Servers, and sustainable workflows. My years of native iOS experience help me avoid "slop layers" and keep AI-generated code maintainable and aligned with solid architecture.

Claude Code Cursor Codex Skills MCP Servers

Projects

These are the apps I've built in my spare time.

Screenshot der Pianoo App

Pianoo
Chords. Scales. Progressions.

Active Closed Source App

A music theory app I built to help with chords, scales, and progressions. Whether you're writing songs or practicing, it's designed to be simple and useful.

Swift SwiftUI Core MIDI Core Audio The Composable Architecture SQLiteData CloudKit In App Purchases

HabitBe
The habit tracker for minimalists.

Active Closed Source App

A simple weekly habit tracker. No fancy features, just tracking what matters. Built with The Composable Architecture, Core Data, CloudKit, and SwiftUI.

SwiftUI The Composable Architecture CoreData WatchKit WidgetKit Combine
Screenshot der HabitBe App

More Projects

Jelly

An open-source library I created for animated view controller transitions in UIKit—both interactive and non-interactive.

Swift UIKit Core Animation Cocoapods
Active Open Source
Soundrocket

My first App Store release from 2015. Discontinued and open-sourced after the API changed.

Objective-C UIKit StoreKit
Inactive Open Source

Work Experience
Where I've worked.

10/2022 - Present
Lead Developer Mobile Applications (iOS) - Aviv
04/2016 - 10/2022
Software Engineer Mobile Applications (iOS) - Immowelt/Immonet
02/2015 - 03/2016
Mobile Application Developer (iOS) - Fashionfreax
08/2013 - 10/2014
Software Developer (C++ / QT / iOS / Android) - IPT Wismar

Education

Master's degree in Multimedia Engineering, Hochschule Wismar

Bachelor's degree in Multimedia Engineering, Hochschule Wismar

My studies covered microprocessor technology, image processing, computer graphics, audio technologies, system programming, networking, and application development.

Blog & Publications

I haven't written new posts recently—focusing on building apps instead. Here are some articles I wrote about iOS development.

Async Await Banner

Learn and Master the Basics of Structured Concurrent Programming

Published on February 22, 2022

 Combine Banner

Learn & Master the Basics of Combine in 5 Minutes

Published on March 12, 2020

 Push Notification Banner

Learn & Master iOS Remote Push Notifications in 10 Minutes

Published on July 10, 2019

More Articles:

Learn & Master the Basics of IGListKit in 10 Minutes (March 6, 2018) Learn & Master the Basics of RxSwift in 10 Minutes (March 7, 2017) iOS Code Signing and Provisioning in a Nutshell (March 30, 2016)

Get in touch

If you want to talk about iOS development, my projects, or anything else, feel free to get in touch.

Contact me.