Stephen O'Connor, iOS Developer in Berlin, Germany
Stephen O'Connor

iOS Developer in Berlin, Germany

Member since February 10, 2021
Stephen has specialized in iOS design and development since 2012. He has delivered a wide array of groundbreaking apps for clients, ranging from individuals to some of Germany's largest companies in the automotive and other sectors. The products he invents are exceptionally well-designed and usable because he understands customers' needs, collaborates closely with stakeholders, and responds to ongoing user feedback. Stephen values customer satisfaction, team harmony, integrity, and reliability.
Stephen is now available for hire


  • Freelance
    Xcode, Objective-C, Swift, Postman, Slack, Affinity Photo, Terminal, Bash...
  • Wiwicon GmbH
    App Design, UX Design, iOS UX Design, Objective-C, iOS, Xcode, Meetings...
  • Giveatoast GmbH
    Xcode, Objective-C, PaintCode, Adobe Photoshop, Mobile Development, iOS SDK...



Berlin, Germany



Preferred Environment

Xcode, Slack, Affinity Photo, Terminal, Postman, Swift, Objective-C, iOS, tvOS

The most amazing...

...thing I've done was to conceive, pitch, and create a whole new product category for a client, which resulted in having my name on a patent.


  • Senior iOS Developer

    2012 - PRESENT
    • Developed countless apps for clients, as a lone developer or a member of a team, and for individual clients up to some of Germany's largest companies.
    • Tracked bugs and tasks, using tools such as Jira, Confluence, Toggl, and Trello.
    • Developed testing strategies and led app deployments and the Apple submission process.
    • Worked effectively in collaborative environments with distributed (remote) workspaces where communication skills were especially important.
    • Consulted on staffing and interview processes and participated in some interviews.
    • Proposed and designed features and UX concepts, sometimes acquiring new clients for the clients I was contracted to.
    • Created proprietary tools and pipelines (command-line tools and Bash scripts) that made UI-related and localization workflows more efficient while reducing dependencies on teammates.
    • Designed entire app features, from UX to software design, during some client engagements.
    • Leveraged many of the Core iOS frameworks on a regular basis, such as Core Data, Core Bluetooth, Core Animation, and AVFoundation (iOS native libraries).
    • Utilized established third-party technologies, such as Realm, Firebase, RestKit, and HockeyApp.
    Technologies: Xcode, Objective-C, Swift, Postman, Slack, Affinity Photo, Terminal, Bash, Firebase, iOS, iOS Native Libraries, Firebase iOS SDK, Mobile Development, iOS SDK, Localization, Google Sheets API, Design Reviews, UX Design, Algorithms, Core MIDI, Model View Viewmodel (MVVM), Carthage, Source Code Review, Prototyping, Git, CocoaPods, Core Bluetooth, SourceTree, Agile Software Development, Unit Testing, Research & Critical Thinking, Software Development, Core Data, REST API Clients, Feature Planning, Design, iOS UX Design, Mobile Apps
  • Head of Product Development

    2013 - 2015
    Wiwicon GmbH
    • Pioneered an entire product and pitched it successfully to the client, one of the largest manufacturers of lighting products in Germany, which was seeking, in part, to compete directly with the Philips Hue product.
    • Invented software UI components so novel in their approach that my name was present on the patent registration.
    • Interfaced and consulted with an associated team on which our work depended. Topics ranged from API design to product functionality considerations.
    • Developed the entire suite of iOS apps related to two products in Objective-C and was responsible for all aspects of their functionality and stability.
    • Served as a product owner concurrently with my role as iOS developer. I had the final word on what would be included in the product, oversaw the progress, and directed the tasks of three teammates—the designer, the intern, and sometimes the boss.
    • Attended regular meetings with the company's principal client, provided status updates, and directed creative ideation workshops.
    • Played a key role in staffing the team with the right people to enable our success.
    • Mastered essential concurrency paradigms, such as OperationQueue and Grand Central Dispatch, as well as data imports to Core Data contexts on background queues. Also required data communication at the socket level as opposed to HTTP.
    Technologies: App Design, UX Design, iOS UX Design, Objective-C, iOS, Xcode, Meetings, Management, Design Reviews, Mobile Development, iOS SDK, iOS Native Libraries, Localization, Git, CocoaPods, Software Development, Core Data, Feature Planning, Design, Mobile Apps
  • Lead iOS Developer

    2012 - 2013
    Giveatoast GmbH
    • Developed the company's product, an iOS app, from the ground up, and was solely responsible for the app's success.
    • Worked in an Agile development team with standups and sprint boards.
    • Participated in high-level meetings about the product roadmap.
    • Advised decision-makers during the hiring process for new team members.
    Technologies: Xcode, Objective-C, PaintCode, Adobe Photoshop, Mobile Development, iOS SDK, iOS Native Libraries, Design Reviews, Git, Software Development, Design, Feature Planning, Mobile Apps
  • Sound Artist

    2005 - 2006
    Electronic Arts
    • Developed an audio project, using the company's proprietary tools that would define how the video game's sound would function interactively with runtime inputs. The approach was very technical but the sound design seemed artistic.
    • Maintained legacy projects built with proprietary tools that pertained to play-by-play sports commentary.
    • Managed and categorized a large amount of audio data in Excel, and contributed to ideation of the next-generation tools for this purpose.
    • Edited a large number of audio voice samples, using typical tools of the day (such as Digidesign Pro Tools, Cubase, and VST), and categorized the samples according to proprietary formats.
    Technologies: Cubase, ProTools, Microsoft Excel
  • Research Associate

    2000 - 2002
    Queen's University, Department of Physics
    • Investigated a very speculative research topic while employed as a student. Within weeks, using whatever means available, I achieved preliminary results that made it clear that we could apply for a grant.
    • Received a $200,000 research grant and served as the principal researcher on the topic of non-destructive testing of Tailor-welded Blanks, a component involved in the automotive manufacturing industry.
    • Held a postdoctoral research position as a bachelor's degree holder, which required special exceptions and arrangements.
    • Presented research findings to large groups at research conferences and published an article as the principal author.
    • Directed the tasks of summer student interns who were employed to assist me in my laboratory.
    • Developed rudimentary signal processing algorithms and designed and constructed the prototype testing apparatus, using a machine shop as required.
    Technologies: LabVIEW, Research, Hardware Design, Instrumentation, Electronics, Public Speaking, Microsoft Excel


  • Roadtrip Music Player

    A Swift-based app designed for people who go on long road trips and want to be able to quickly navigate their offline music collection with a bare minimum of user interaction required (as distracted driving is dangerous).

    I designed and built the app completely solo. It involved heavy use of the AVFoundation and MediaPlayer frameworks; Core Animation APIs; implementation of in-app purchases; and interactions from remote controls, such as Apple headphones or the car steering wheel. The app is currently live on the App Store.


  • Languages

    Swift, Objective-C, Java, Bash, Bash Script
  • Tools

    Xcode, Slack, Terminal, Postman, Git, SourceTree, Affinity Photo, LabVIEW, Adobe Photoshop, Eclipse IDE, Sketch, Zeplin, PaintCode, Cubase, ProTools, Spreadsheets, Microsoft Excel
  • Platforms

    iOS, tvOS, MacOS, Firebase
  • Other

    Research & Critical Thinking, Analysis, Software Development, Mobile Apps, Prototyping, Design, Feature Planning, Mathematics, REST API Clients, AVFoundation, iOS UX Design, Writing & Editing, Source Code Review, Physics, Electronics, 3D Modeling, Algorithms, Game Design, Carthage, App Design, Meetings, Design Reviews, Localization, Research, Hardware Design, Instrumentation, Public Speaking
  • Frameworks

    Core Data, Core Bluetooth, Core MIDI, iOS SDK
  • Libraries/APIs

    CocoaPods, Google Sheets API, Firebase iOS SDK, iOS Native Libraries
  • Paradigms

    Model View Viewmodel (MVVM), Agile Software Development, Mobile Development, Object-oriented Programming (OOP), Unit Testing, UX Design, Management


  • Bachelor's Degree in Computer Science
    2007 - 2010
    University of Applied Sciences (HTW Berlin) - Berlin, Germany
  • Bachelor's Degree in Physics
    1997 - 2000
    Queen's University - Kingston, Ontario, Canada

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