Sebastian Boldt

Sebastian Boldt

iOS Developer since 2012, building apps used by millions of people.

Skills

I’m an iOS engineer with experience across small teams and large international environments.
I focus on clean architecture, modular design, and maintainable code, using SwiftUI, TCA, and the Point-Free ecosystem.
I value quality, collaboration, and the responsible use of LLMs, aiming for simple, testable, and easy-to-maintain solutions.
I rely on clear documentation and consistent communication to help teams move quickly and confidently.
Swift SwiftUI Objective-C UIKit Point-Free Ecosystem The Composable Architecture (TCA) Modular Architecture (SPM) Scalable App Modularization using SPM White-Labeling Unit Testing Continuous Integration Mono-Repo & Multi-Repo Workflows Large International Team Collaboration Experienced Mentor and Presenter Responsible AI & LLM Usage in Engineering

Projects

Pianoo
Pianoo
Coming soon Closed source App

Pianoo — details coming soon.

Swift SwiftUI SQLiteData CloudKit StoreKit The Composable Architecture Xcode Cloud
HabitBe
HabitBe
Active Closed Source App

HabitBe is a lightweight weekly habit tracker with no frills. It was developed using a reactive MVVM pattern and modern technologies such as SwiftUI and Combine.

Swift SwiftUI TCA - Composable Architecture CoreData CloudKit ClockKit WatchKit StoreKit WidgetKit Combine The Composable Architecture Xcode Cloud
Jelly
Jelly
Active Open Source Framework

A library for animated, non-interactive and interactive view controller transitions and presentations, focused on a simple yet flexible API.

Swift UIKit Core Animation Cocoapods
Soundrocket
Soundrocket
Inactive Open Source App

This was my first app to reach the App Store in 2015. After SoundCloud discontinued the connected API a few months later, I stopped maintaining the project and released it as open source.

Objective-C UIKit StoreKit
Immowelt
Immowelt
Active Closed Source App

I worked at Immowelt for almost five years and was heavily involved in the redevelopment of the iOS app — from the UI to low-level persistence and networking layers. At Immowelt I collaborated with many teams across departments and learned a great deal about the structure and processes of a large company.

Swift Realm UIKit MapKit WidgetKit Core Animation PromiseKit VIPER Clean Code Fastlane Quick Nimble KIF Grand Central Dispatch Swift Package Manager Cocoapods Carthage Continuous Integration
Fashionfreax
Fashionfreax
Inactive Closed Source App

I worked on the Fashionfreax app for one and a half years, handling everything from integrating payment service providers to implementing complex UI elements.

Objective-C UIKit Fastlane MVC - Massive Viewcontroller StoreKit Stripe

Blog

I stopped writing new posts to focus on other projects and, partly, because of the rise of large language models. Here are some of my earlier articles:

Async await

Learn and Master the Basics of Structured Concurrent Programming

Published on February 22, 2022

Combine

Learn & Master the Basics of Combine in 5 Minutes

Published on March 12, 2020

Push

Learn & Master iOS Remote Push Notifications in 10 Minutes

Published on July 10, 2019

IGListKit

Learn & Master the Basics of IGListKit in 10 Minutes

Published on March 6, 2018

Push

Learn & Master the Basics of RxSwift in 10 Minutes

Published on March 7, 2017

Jelly

My first Cocoapod is here Jelly 1.0

Published on November 21, 2016

Optional

Swift! Optionals?

Published on June 24, 2016

Signing

iOS Code Signing and Provisioning in a Nutshell

Published on March 30, 2016

Toolkit

My iOS Development Toolkit 2018

Published on March 22, 2016

Work Experience

10/2022 - Present
Lead Developer Mobile Applications (iOS) @ Aviv
04/2016 - 10/2022
Software Engineer Mobile Applications (iOS) @ Immowelt
02/2015 - 03/2016
Mobile Application Developer (iOS) @ Fashionfreax
08/2013 - 10/2014
Software Developer (C++ / QT / iOS / Android) @ IPT Wismar
03/2012 - 08/2012
Internship (Ruby on Rails & iOS) @ BringWasMit
01/2012 - 06/2012
Student associate (Leading C++ Labs) @ Hochschule Wismar

Education

Master's degree in Multimedia Engineering, Hochschule Wismar

Bachelor's degree in Multimedia Engineering, Hochschule Wismar

Multimedia Engineering covers microprocessor technology and electronics, image processing and computer graphics, audio and voice technologies, system- and hardware-dependent programming, networking and communications, and application and web programming.