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Olivier CastilleOC

Olivier Castille

Senior iOS Engineer | Fast Delivering

€600/day
Paris, FR
15+ years

Average response time: 1 hour

Freelancer profile translated to English.
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About Olivier

Lead iOS with 15 years of experience in designing and delivering high-impact mobile applications. I support start-ups, scale-ups, and large corporations on topics combining technical requirements, execution quality, and product vision. Specializing in Swift, SwiftUI, and modular architectures, I enjoy building performant, high-quality, and sustainable applications, while actively contributing to product decisions and team dynamics.
  • French

    Native or bilingual

  • English

    Fluent

Can work on-site
Paris (up to 10km), Lyon (up to 10km)

Experience

  • Edailabs
    Lead iOS Tech
    SOFTWARE PUBLISHING
    December 2023 - October 2025 (1 year and 10 months)
    Paris, France
    Creation of the language learning applicationEmma**, using a 3D avatar, AI, and speech-to-text/text-to-speech technologies to manage voice interactions with the user. **€5M funding roundin late 2025 and€3M ARRover one year.
    • Development of modular, testable features with A/B testing to determine the best conversion rates: AI calls, interactive lessons, onboarding, evolving rewards...
    • Modularity of the code structure into packages to allow excellent isolation, testability, factorization, and code reuse (with another 3D/AI coaching POC)
    • Performance optimization to ensure smooth management of the 3D view display (fullscreen, picture in picture) while maintaining SwiftUI responsiveness
    • Implementation of rapid iterations with a daily testable internal release and weekly production deployments

    My impact:Proactive in design and features, rapid development enabling daily iterations, modular project architecture ensuring code quality without slowing down delivery. Training and knowledge transfer to new developers joining the project.

    Tech:Swift, SwiftUI, Unity, Combine, gRPC, sockets, Firebase, MVVM + Coordinator, clean architecture, CI via Bitrise, analytics + A/B testing via Amplitude, native paywalls via Superwall, SwiftLint

    App:emma-learn.com
    Swift SwiftUI Artificial Intelligence Firebase Unity 3D
  • Alma Pay
    Senior iOS Software Engineer
    BANKING AND INSURANCE
    December 2021 - May 2023 (1 year and 5 months)
    Paris, France
    Creation of the iOS application for the micro-credit solution **Alma**.
    • Development of the three main features: a marketplace bringing together Alma's partner brands, a management space for the Mastercard virtual credit card allowing payment in installments with all merchants, a space for tracking ongoing payment schedules (early payment, deferral of installments, incident management)
    • Modularity of the code structure into packages allowing excellent isolation, testability, factorization, and code reuse
    • Creation of a complete KYC journey: identity document scanning, customer information entry, verification of customer bank accounts, creation of a dedicated bank account for the virtual card
    • Rapid iterations with a weekly release, monthly production deployments
    • Complete application redesign during the project to match the brand's new identity

    My impact:Pixel perfectionist to respect Figma designs, proactive in design and features, modular code structure to ensure solid code quality and facilitate unit testing.

    Tech:Swift, SwiftUI, Combine, MVVM + Coordinator, clean architecture, REST backend, CI via Bitrise, analytics + A/B testing via Amplitude, unit tests, SwiftLint, SwiftGen

    App:
    Swift iOS SwiftUI Amplitude Combine
  • Eurosport
    iOS Software Engineer/Co-lead Tech
    SPORTS
    June 2019 - May 2021 (1 year and 11 months)
    92130 Issy-les-Moulineaux, France
    Complete redesign of the iOS application for the audiovisual group Eurosport, allowing for a technical overhaul of the existing system and the adoption of the brand's rebranding. Worldwide availability with over500k daily users**, more than **50 editorialized sports**, 13 languages supported, **live streamingof all TV channels & **replays**, special versions for following the Olympic Games.
    • Design and evolution of the project's modular architecture in MVVM-C respecting clean architecture to ensure modularity, reusability, and code quality from the foundations.
    • Development of a complete UI templating system based on atomic design (atoms, molecules, organisms) via custom collection view layouts, horizontal rails, and triggers, to standardize and simplify the management of all screens.
    • Responsible for the video player layer: live streams and replays in secure HLS, Chromecast/AirPlay 2 support, picture-in-picture, system integration via Remote Command Center, management of video advertising (Freewheel) and analytics (MUX, Adobe Experience) — including special coverage of the Olympic Games.
    • Daily work in English with product, QA, and board teams based in London and India, in a demanding international context.

    My impact:Architectural and visual redesign of a high-traffic international application, complete ownership of the premium video player, implementation of a scalable design system, and maintenance of a high level of quality via CI and peer reviews.

    Tech:Swift 5, MVVM, dependency injection, dynamic frameworks, GraphQL, atomic design, Fastlane, CircleCI, SonarQube, GitHub Enterprise, InVision
    iOS SwiftUI Live Streaming Pixel Perfect HLS

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Education

  • Architecture et Management des Systèmes d'Information
    exia.cesi - Ecole supérieure d’informatique Nancy
    2011

Skill set

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