Under the brands, Web.de, GMX, 1und1, and Mail.com, United Internet AG offers email and cloud services that are used every day by millions of users on their iPhones. The white-label app has historically grown since 2010 and as part of the 10-person team, besides adding new features to the app, I refactored legacy code and increased test coverage.
Features
Email and cloud access
Compose email
Email and cloud sync
News
Contact
Multiple account management
Synchronization
Notifications
Premium features
Ads
Technologies used
UIKit
SwiftUI
Combine
VIPER
Unit tests
UI tests
Snapshot tests
Fastlane
Cocoapods
MailCore
Mar 2021 - Dec 2021
10 months
Germany
Freelance iOS Developer
D4L data4life gGmbH
The Data4Life app helps users manage their health, gain new knowledge, and contribute to research.
The biggest challenge in this project was to change the app's UI from UIKit to SwiftUI during ongoing development and change the overall architecture from VIPER to Composable Architecture. This was achieved by modularizing the app into over 50 Swift packages and then gradually transforming them.
In addition to the architecture and development part, the job involved coaching the staff in Composable Architecture and SwiftUI by means of pair programming and in-depth sessions.
Features
Keep track of symptoms
Participate in studies
Store medical documents digitally
Knowledge base
Technologies used
UIKit
SwiftUI
Combine
VIPER
Composable Architecture
Unit tests
Fastlane
SnapKit
Swift Package Manager
Sentry
Feb 2021 - Dec 2021
11 months
Germany
Freelance iOS Developer
Sparkasse S-Markt & Mehrwert GmbH
After having worked on the project already in 2019/2020, I re-joined the app team of Sparkasse's agency S-Markt & Mehrwert GmbH to support them on one of their projects, a white label customer loyalty app they're offering to their partners, one of which is Hamburger Sparkasse's app HaspaJoker.
This time the job mainly involved consulting, coaching, and weekly code reviews.
Aug 2020 - Oct 2020
3 months
Germany
Freelance iOS Developer
12grapes GmbH
12grapes GmbH is the company behind the app Bunch, an AI coach that makes it easy to learn and grow your leadership skills with bite-sized daily tips.
I joined Bunch in August 2020 to help develop new features and reduce the technical depth to make the app more performant, maintainable, and testable at the same time.
To achieve this, I've built a backend with a REST API and outsourced some of the app's business logic.
Furthermore, I introduced Functional Reactive Programming in an MVVM setup.
Features
Multi-step onboarding
Search
Explore Content
Gamification
User profiles
Read or listen to tips
Social sharing
Calendar integration
Technologies used
SwiftUI
Combine
MVVM
In-App Purchase Subscriptions
Fastlane
Travis CI
Unit tests
Firebase Firestore
Firebase Cloud Functions
Firebase Authentication
Firebase Cloud Storage
Google App Engine
Jun 2020 - Aug 2020
3 months
Germany
Freelance iOS Developer
sonamedic GmbH
Technologies used
SwiftUI
Combine
AVFoundation
Swift ComposableArchitecture
In-App Purchase Subscriptions
Fastlane
Firebase
Unit tests
Dec 2019 - May 2020
6 months
Germany
Freelance iOS Developer
Sparkasse S-Markt & Mehrwert GmbH
In December 2019 I joined the app team of Sparkasse's agency S-Markt & Mehrwert GmbH to support them on one of their projects, a white label customer loyalty app they're offering to their partners, one of which is Hamburger Sparkasse's app HaspaJoker.
Through the app, customers get special offers and discounts from local partners, can book travel/concert tickets and benefit from a variety of other perks and services.
The agile scrum team consisted of 5 iOS, 4 Android as well as 4 backend developers and was working predominantly remotely.
Some of the work I did included refactoring and consolidating the codebase to be testable, introducing Screenshot tests, automating tasks, and implementing new features.
Technologies used
XCode
RxSwift
Fastlane
Alamofire
SwiftLint
SnapKit
MVVM
REST-Api
AppCenter
SwiftGen
Coordinator
Snapshot tests
Unit tests
GIT
Scrum
Nov 2019 - Feb 2021
1 year 4 months
Freelance iOS Developer
Splay, Inc.
The app enables selected users to upload single or multiple photos combined with text to a public feed, which automatically deletes the content after two days. In addition, the app allows one user to stream live videos simultaneously, which then appear in the feed. Viewers of the stream can send emoji reactions which then move across the screen for all participants to see. Besides photos, selected users can also post products for sale in the feed which are paid for via Apple Pay and can even be purchased by unregistered users.
A special feature of the app is that all actions are visible to other users in real-time. For example, if a user writes a text, other users can watch the author writing it even before it is published.
Features
Live video streaming
Live updates through WebSocket
Sign in with Apple
(Multiple) Image posting
Text posting
Photo cropping
Commenting
Mentioning users in comments
Technologies used
UIKit
WebSocket
WebRTC
Mediasoup
RxSwift
Fastlane
SnapKit
Push Notifications
Apple Pay
Stripe
MVVM
Unit tests
Jul 2019 - Nov 2019
5 months
Germany
Freelance iOS Swift Developer
Spielworks GmbH
Spielworks hired me to kick-start their product "Wombat" for iOS.
For this greenfield project, I did both the architecture and the implementation of the beta version and later hired another developer who eventually took the project over.
The app is the first EOS wallet built for everyday use and simplifies the creation of EOS accounts through a three-step onboarding process. It automatically encrypts and stores the private key in the cloud and makes sending/receiving EOS tokens a breeze.
One of the core features of the app is the DAPP Browser that acts as a proxy between DAPP and the EOS account and provides a streamlined user-interface to sign transactions.
Features
Login
EOS account creation
Send/Receive EOS tokens
Sign transactions
SDK for third-party apps
Manage EOS keys
Unlock private key
Prime subscription
EOS resources overview
Technologies used
In-App-Purchases
EOS Blockchain
AES Cryptography
Sign in with Apple, Facebook, Twitter and Email
Firebase
Crashlytics
RxSwift
MVVM
Google Drive
Dropbox
Unit tests
Jan 2019 - Jun 2019
6 months
Germany
Freelance App and Backend Developer
Fitness First Germany GmbH (via anywhereinside UG)
Together with another developer I’ve built the fitness video portal “My Fitness Video” for Fitness First.
The project was set up with high scalability and security in mind and was built entirely with various components of Amazon Web Services (AWS).
It consists of three main parts. Firstly the backend, where one of the bigger challenges was, to implement the whole payment and subscription process. Secondly the web app, a server-side rendered vue.js single page application, and thirdly the content and customer management system for administrators.
After having helped out Vantik as a freelancer end of 2017, I joined full-time in 2018 to build up the entire frontend stack and team.
Vantik is an investment-based retirement savings product (private pension).
Since Vantik is a banking product, highest priority in all layers of the stack was security and compliance with the German federal financial supervisory authority (BaFin).
Boston Consulting Group (via functionalaesthetics GmbH)
Together with a team of developers put together by functionalaesthetics, I was working on the iOS swift app (universal - iPhone & iPad) for Boston Consulting Group’s client smile.direct, a Swiss insurance company.
The app was designed to help families planning their everyday life.
The main part of the app is an elaborate calendar, heavily optimized for easy user experience on both the iPad and iPhone.
Furthermore, family members have profiles and can easily communicate through private messages.
Features (excerpt)
Calendar component
Create & edit events
Comment
Animated onboarding
Create & edit task lists
Import calendars
Sharing
Push notifications
User registration & login
Reset & change password
Family setup
Private messages
Change app theme
Technologies used
Swift
UIKit
Fastlane
RxSwift
MVVM
Reactive programming
Alamofire
AlamofireImage
SnapKit
SwiftLint
Firebase
BuddyBuild
Core Text
Core Telephony
Quartz Core
AVFoundation
Core Media
Core Video
Dec 2015 - May 2017
1 year 6 months
Germany
iOS Swift Developer
Wine in Black GmbH
Together with another app developer I’ve built the native iOS swift (universal - iPhone & iPad) app for Wine in Black, a wine e-commerce company.
Due to the fact that Wine in Black is a curated shop with a limited, constantly changing assortment, the app stores all active products on the device and syncs with the server on startup so that all interactions with products such as browse, search or filter are instant and do not require a network connection.
Besides working on the iOS app, another part of the job was building a new REST API. This was necessary because the existing shop system was being replaced during the project.
For universeiscool, I built the social image sharing app FOYER.
It enables the user to combine text and photos into a story and a layout algorithm takes care that stories look unique and good on any device.
An integrated image editor provides an easy way to get the most out of the pictures and social features such as share, like and comment make sure that stories get the attention they deserve.
The social feed channelizes the stories created or shared by followed users and the discover section in the app exposes stories of users from outside the user’s network.
Features
Login
Registration
Animated onboarding flow
Story page
Story editor
Image editor and picker
Social feed
Like, share, comment story
Discover section (stories & users)
Profile
Push notifications
Web app for cross-platform use
Technologies used
App: Swift & Objective-C, UIKit, Core Image, Core Graphics, Core Animation, Alamofire, MVC, Unit tests