Sebastian Boldt

sebastian boldt

iOS Developer since 2012

I am a mobile software architect and developer specializing in iOS. Passionate about creating awesome user experiences, designing beautiful api and user interfaces, and writing maintainable, structured, and best-practice orientated code. Continuously trying to improve skills and learn new technologies.
Mobile Development iOS Swift SwiftUI Combine Objective-C Software Engineering Multithreaded Programming Xcode Professional GoF - Gang of Four Design Patterns Code Signing and Provisioning Cocoapods Carthage Swift Package Manager Catalyst Fastlane Git Gitflow Workflow RxSwift MVC / MVVM / VIPER Unit & UI Testing Continuous Integration Realm Vapor Server-side Swift


Active Closed Source App

HabitBe is the perfect lightweight weekly Habit Tracker with no frills. Developed with a reactive MVVM Pattern using brand new technologies like SwiftUI and Combine.

Swift SwiftUI CoreData CloudKit ClockKit WatchKit StoreKit WidgetKit Combine MVVM Clean Code iPad support Xcode Server
Active Open Source Framework

A library for animated, non-interactive & interactive viewcontroller transitions and presentations with the focus on a simple and yet flexible API.

Swift UIKit Core Animation Cocoapods
Inactive Open Source App

This is my first app that made it into the Appstore in 2015. Since Soundcloud didn't support the connected API some months later, I quit maintaining the project but made it open source.

Objective-C UIKit StoreKit
Active Closed Source App

I have been working at Immowelt for almost 5 years and I am significantly involved in the redevelopment of the iOS app, all the way from UI to the low level persistence or networking layers. At Immowelt, I am working with many teams from different departments and also learned a lot about the setup and structure of a big company.

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

I worked on the Fashionfreax app for 1.5 years, helping with everything from integrating payment service providers to programming complex UI elements.

Objective-C UIKit Fastlane MVC - Massive Viewcontroller StoreKit Stripe


Async await

Learn and Master ⚔️ the Basics of Structured Concurrent Programming in Swift in 15 Minutes

Published on February 22, 2022

WWDC 2021 has brought some exciting enhancements to Swift. One of the most interesting are the new mechanisms around async and await. If you are interested in this and don’t want to watch all the session videos to understand how the new toolset works, you are at the right place. I tried to extract the most important facts of all the new features in this article with easy to understand code examples. If you want to dive deeper I included a list of tutorials and references around this topic.


Learn & Master the Basics of Combine in 5 Minutes

Published on March 12, 2020

Because RxSwift and Combine have so much in common I thought it would be a great idea to adapt the things I know about RxSwift and use them to create something new. This is an article based on one of my most successful articles here on Medium (Learn and Master Rx-Swift). More than 140.000 Impressions so far. That’s Amazing, thank you so much.


Learn & Master iOS Remote Push Notifications in 10 Minutes

Published on July 10, 2019

Remote Push notifications enable developers to present information to their users outside the app and to redirect them to the app if necessary. Important events will arrive in the form of badges, sounds or banners. But be careful here, too many push notifications may lower the retention and deter your users. When and how push notifications are displayed should be well considered, inflationary and unimportant notifications can mean death for a good app.


Learn & Master the Basics of IGListKit in 10 Minutes

Published on March 6, 2018

Anyone who has ever implemented dynamic lists in iOS will probably know that the official approach has some difficulties. Datastore and view layer have to be synchronized manually and during the update a certain order should be kept to avoid crashes. In addition, the classical approach is tempting to encapsulate the logic of the different cells in a large data source rather than separating them sensibly. To prevent these problems IGListKit was created. A framework developed by the Instagram team.


Learn & Master the Basics of RxSwift in 10 Minutes

Published on March 7, 2017

Every programmer should have heard of Rx. Whether it happened at the last developer conference or while reading a fresh blog article like this one 😎. It is almost impossible not to have heard of it, but what exactly is Reactive Programming?


My first Cocoapod is here  — Jelly 1.0

Published on November 21, 2016

Yay, my first Pod is available for everyone. Jelly 1.0, a Viewcontroller-Transition-Animation framework that is super easy to use. I always wanted to have a public Github repository other people can contribute to and I found myself writing custom Viewcontroller-Transition-Code over and over again. So wouldn’t it be a great idea to create an easy to use Pod for that?


Swift! Optionals?

Published on June 24, 2016

If you are new to swift and to the concept of Optionals you may think that it's a little bit strange to have a special type for representing "something" or "nothing", but if you get the hang it comes really handy in a lot of situations.


iOS Code Signing and Provisioning in a Nutshell

Published on March 30, 2016

I am developing Apps for more than 3 years now and 1 thing that still annoys me is Code Signing and Provisioning in iOS. What are Signing Identities? Why do I need to create Provisioning Profiles and care about such things as a developer? If you don’t have any good answers for those questions and really don’t want to read through the Apple Docs, this hopefully is the article that exposes the whole process for you and for me as a reference in less than 5 Minutes.


My iOS Development Toolkit 2018

Published on March 22, 2016

This is a curated list of iOS Development Tools, Websites, Services and Frameworks I am currently using.

work experience

04/2016 - today
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 (C++) @ Hochschule Wismar


Multimedia Engineering - Master's degree @ Hochschule Wismar

Multimedia Engineering - Bachelor's degree @ Hochschule Wismar

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