Senior iOS Engineer · Native Swift & SwiftUI · Kotlin Multiplatform

Nine years of native iOS — health, automotive, mobility.

I build and modernize large-scale Swift codebases. Most recently I worked on Germany's electronic patient record (ePA) — a white-label iOS app serving 15+ health insurers, developed with 40+ engineers.

M.Sc. Information Systems, TUM
Remote (EU/US overlap) · EU work authorization

Selected Work

2024 – 2026

IBM ePA — electronic patient record

Worked on Germany's first electronic health record: one IBM white-label codebase powering the apps of 15+ statutory and private health insurers. Across three teams in a project of 40+ engineers, my focus was accessibility (VoiceOver, Full Keyboard Access), test-suite and CI reliability across 20+ modules, ePA document rendering on a shared KMP layer, authentication and private-insurer client apps, the iOS 26 / Liquid Glass migration, and the SBOM supply-chain pipeline — 129 merged PRs across five repos.

AccessibilityTest reliability / CIKotlin MultiplatformAuthenticationiOS 26 / Liquid GlassSBOM / supply-chainDesign systemWhite-labelSwiftUI

2022 – 2024

BARMER eCare

Award-winning patient-record app for one of Germany's largest insurers. In a team of eight, I drove architectural improvements and the modularization into feature packages, ported the app from UIKit to SwiftUI, built the Mental Health feature on a shared Kotlin Multiplatform model layer, added dark-mode support across the whole app, and improved the snapshot-test suite — working closely with the UX-award-winning design team.

UIKit → SwiftUI migrationDark modeKotlin Multiplatform (KMM)Modular architectureSnapshot testingDesign tokensWhite-labelCombine

App Store ↗

2021 – 2022

Public-transport app platform (Siemens subsidiary)

White-label platform powering 70 individually configurable transit apps from one codebase (HaCon, a Siemens Mobility subsidiary). In an iOS team of ~20, I built the platform's first production TCA + SwiftUI screens inside a 75 % Objective-C host, implemented the eMobil booking flow in the shared base, delivered ~80 tickets across 20+ customer apps, ran upstream maintenance integrations into customer forks, owned seven App Store deliveries, and contributed tariff and ticketing features to the base — with snapshot tests on GitLab CI and fastlane delivery.

TCA + SwiftUIWhite-label (70 apps)Maintenance integrationsApp Store deliveryObj-C → Swift migrationModular architectureSnapshot testingGitLab CIfastlane

2019 – 2021

Mercedes-Benz Advanced Control

Camper-van smart-home app (roof, awning, heating, lights, levelling, ...) talking to the vehicle's control unit over BLE. In a five-person team I integrated the security layer (ECDH key exchange, AES-CCM encryption, HMAC authentication), hardened the BLE stack and the config-driven UI that renders widgets from JSON transferred over Bluetooth, designed the error-handling concept and grew the app's state machine from 6 to 11 states under test, and shipped four App Store releases (1.0 → 2.0). For part of the project I was the lead iOS engineer and Scrum Master.

CoreBluetooth (BLE)ECDH / AES-CCM / HMACCryptoSwiftKeychainState machinesConfig-driven UIOwn frameworks4 App Store releasesAzure DevOps

App Store ↗mercedes-benz.com ↗

2018 – 2019

BMW Motorrad Connected & BMW One Connected

Motorcycle navigation optimized for riders — HERE/TomTom NavKit routing, GPX route import, head-unit communication over ZeroC ICE, CoreAudio guidance — in a 580k-line codebase, plus feature work and Objective-C → Swift migration on BMW's connected-car app (RxSwift, Swinject) in a 30+ developer, two-continent program.

HERE MapsTomTom NavKitGPX importCoreAudioZeroC ICEObj-C → Swift migrationRxSwiftSwinject

App Store ↗

2020 – 2023

Ubermind Track — indie app

Solo side project, end to end: idea, design, architecture, development, TestFlight betas and App Store release. An app for tracking personal self-experiments.

CoreDataSolo product ownershipTestFlight → App StoreProduct design

App Store ↗

Earlier work (2015 – 2022)

2017
HieroQuest — master's thesis at TUM: an educational game teaching Egyptian hieroglyphs, incl. an experimental learning study (Unity 3D).
2016 – 17
LeadApp, Weptun — lead developer of an iOS lead-management client with business-card scanning.
2016
KRI SWOOP — stroke-patient workflow tracking with BLE beacons at hospital Rechts der Isar; team coach & Scrum Master.
2015 – 16
iWash — washing-label image recognition (OpenCV) and NFC for B/S/H; lead developer in a team of 7.

What I Bring

Architecture & migrations

Modernising grown codebases without stopping feature work — UIKit → SwiftUI, iOS 26 / Liquid Glass, refactoring, tech-debt strategy, making a 20+-module test suite deterministic.

Regulated environments

Health and automotive: sensitive data, authentication, accessibility and security requirements as daily business.

Hard technical problems

BLE protocol design, applied cryptography, state machines, config-driven UI — the parts most app developers avoid.

Teams at scale

Comfortable in 40+ engineer codebases; experience as Scrum Master, team coach and onboarding mentor.

AI-native development

Agentic coding tools (Claude Code, Cursor) in the daily loop — LLM-accelerated refactoring, tests and docs, always gated by a senior engineer's review.

End-to-end ownership

Shipped a solo indie app from idea to App Store release — comfortable owning products, not just tickets.

What Colleagues Say

"Dennis covers a remarkable range — from the architecture of our white-label app through complete UI features and thoughtful accessibility to CI automation that made our whole workflow more efficient. […] You can rely on Dennis 100%. When problems come up he doesn't go quiet — he communicates openly and works toward a solution. Any team looking for an iOS developer who delivers independently and takes ownership is extremely well served with him."

Sebastian Maschinski — iOS Lead Engineer, IBM ePA · LinkedIn recommendation, June 2026 (translated from German)

Beyond Code

I write about productivity systems: author of The Path to a Productive Life and the blog Scale-Smart Me.

Tech Stack

SwiftSwift ConcurrencyObjective-CKotlin MultiplatformSQLSwiftUIUIKitCombineAccessibilityVoiceOver / Full Keyboard AccessDark modeLiquid Glass (iOS 26)Design tokensLocalizationSOLIDClean architectureMVVMTCADependency injectionMulti-module designState machinesDesign patternsCoreBluetooth (BLE)CoreDataCoreAudioCoreLocationMapKitPush / APNsUniversal LinksKeychain / SecurityApplied cryptographyECDH / AES-CCM / HMACSSL pinningBiometric authApp Attest / DeviceCheckOWASP MASVSXCTestSwift TestingUnit testingSnapshot testingUI testingAppiumTestFlightInstrumentsXcodeSwift Package ManagerCocoaPodsfastlaneSwiftLint / SwiftFormatGit / GitHubGitHub ActionsXcode CloudGitLab CIJenkinsAzure DevOpsApp Store ConnectCrashlytics / SentrySBOMDependency TrackFigmaClaude CodeCursorGitHub CopilotAI-native developmentLLM-accelerated refactoringScrumKanbanCode reviewREST / JSONAlamofireOAuth

Contact

Open to remote roles with EU/US overlap. German citizen — authorized to work across the EU, no visa sponsorship required. German (native) · English (fluent).

dennisnehrenheim90 [at] gmail [dot] com

gh/ GrowthPilgrim in/ dennis-nehrenheim