Dino Bartošak, Software Developer in Zagreb, Croatia
Dino Bartošak

Software Developer in Zagreb, Croatia

Member since June 29, 2016
As a software engineer, Dino has specialized his skills in building mobile apps. He has worked with teams of various sizes and developed skills in building products iteratively, developed analytical abilities and prototyping techniques. He likes clean, modular, and maintainable code written to be reliable in all conditions. iOS is his platform of choice.
Dino is now available for hire



  • REST 12 years
  • Object-oriented Programming (OOP) 10 years
  • Core Animation 10 years
  • Git 10 years
  • Objective-C 10 years
  • Xcode 10 years
  • iOS 10 years
  • Swift 6 years


Zagreb, Croatia



Preferred Environment

Git, Swift, Xcode, iOS

The most amazing...

...thing I've made is LooksGood, an app built from scratch, full of subtle UX details and animations which make the app a pleasure to use.


  • iOS/Swift Developer

    2021 - 2022
    Circular, LLC (via Toptal)
    • Developed a content planner module for the Pixelcut app, which enabled users to schedule their posts on Instagram.
    • Developed social login feature, which allowed users to login into the app via Google, Facebook, Apple, or classic email.
    • Implemented various screens based on designs created in the Sketch app.
    • Tracked and fixed bugs using Linear as a reporting tool.
    Technologies: Swift, iOS, Firebase iOS SDK, Firebase, Xcode, iOS Instruments, UIKit, Core Animation, Google Login, Facebook Login, gRPC, Sketch, Figma
  • iOS Engineer

    2020 - 2021
    Jumprope Inc (via Toptal)
    • Worked on lots of app features. Improved existing and added new features. Rewrote video editor feature where I implemented a custom collection view to add dynamics to the transitions of UI elements.
    • Tracked and optimized app for memory leaks using iOS Instruments.
    • Led a project of migrating an app from ReactNative to native iOS. Rewrote ReactNative screens and functionalities in native iOS using Swift programming language.
    • Led a subproject to create a desktop app where I used Mac Catalyst. Made sure that no regressions were added to the existing mobile application while adjusting and implementing desktop-specific features in the same codebase.
    Technologies: Swift, Xcode, iOS Instruments, AVFoundation, UIKit, RealmSwift, GraphQL
  • iOS Developer

    2019 - 2019
    2705433 Ontario Limited (via Toptal)
    • Built an app for organizing live social events in a team of two.
    • Created various UI components like forms and messages and integrated them with the app.
    • Made sure that all code is clean has more straightforward maintenance.
    Technologies: UIKit, TestFlight, RxSwift, Model View Viewmodel (MVVM), GraphQL, REST, Git, Swift
  • Senior iOS Architect

    2019 - 2019
    Zuvy, Inc. (via Toptal)
    • Collected requirements from the client and translated them into subtasks.
    • Built a task and delivered a social iOS app from scratch based on requirements and UI designs.
    • Helped the back-end developer in defining the API and integrating the app with the API.
    • Configured beta tester distribution via TestFlight.
    Technologies: UIKit, Maps, TestFlight, RxSwift, Model View Viewmodel (MVVM), REST, Git, Swift, UI Animation
  • iOS Developer

    2019 - 2019
    Countalytics (via Toptal)
    • Built a photo capturing iOS app prototype that uses camera functionalities.
    • Connected the app with a back-end API that other developers developed.
    • Configured beta tester distribution via TestFlight.
    Technologies: UIKit, TestFlight, RxSwift, Model View Viewmodel (MVVM), REST, Git, Swift
  • iOS Developer

    2018 - 2019
    Selotsoft (via Toptal)
    • Built a hashtag messaging iOS app from scratch in a team of two iOS developers.
    • Added new features and iterated through multiple UI/UX prototypes.
    • Handled the UI/UX part of the project while also contributing to the API layer.
    • Configured the beta tester distribution via TestFlight.
    Technologies: UIKit, TestFlight, RxSwift, Model View Viewmodel (MVVM), REST, Git, Swift, UI Animation
  • iOS Developer

    2018 - 2018
    Knoit (via Toptal)
    • Developed an iOS app prototype for a conversation hub, organizing conversations across channels like social and email into feeds.
    • Built a UI component for interactive creation of photo mosaics similar to the Instagram Layout app.
    • Configured beta tester distribution via TestFlight.
    Technologies: UIKit, TestFlight, RxSwift, Model View Viewmodel (MVVM), REST, Git, Swift, UI Animation
  • Senior iOS Developer

    2016 - 2018
    Sports Insights (via Toptal)
    • Built the iOS app Sports Insights from scratch in Swift using MVVM design pattern.
    • Implemented all screens based on mockups and feedback from the client.
    • Connected the application with the back-end API while communicating API compatibility and changes with the back-end developer. The app screencast video can be seen here: https://vimeo.com/272246541.
    Technologies: iOS Instruments, Analytics, Crashlytics, StoreKit, Core Animation, Core Graphics, CocoaPods, Xcode, Swift, iOS
  • iOS Developer

    2016 - 2017
    Airmee (via Toptal)
    • Created an iOS application prototype in Swift for the product MVP phase.
    • Implemented a UI based on the provided mockups.
    • Connected the application with the back-end API.
    Technologies: iOS Instruments, Maps, Core Animation, Core Graphics, CocoaPods, Xcode, Swift, iOS
  • Senior iOS Developer

    2016 - 2016
    Docler USA, LLC (via Toptal)
    • Created a custom UICollectionView with functionality to drag and drop cells between multiple collections. Screencast: http://y2u.be/PVP-aCQyuTE.
    • Refactored host iOS application code that was using an outdated open source library for the drag and drop functionality.
    • Integrated a new component into the host app.
    Technologies: Swift, Objective-C, Xcode, iOS
  • iOS Developer

    2016 - 2016
    Piqua (via Toptal)
    • Created a SnapChat-like feature for photo/video capture (tap, long press) and edit. Screencast (temporary icons used during development): http://y2u.be/vEahlxVxT7Y.
    • Translated design sketches for new features into app screens.
    • Added different elements (text, finger drawing, sticker) as photo/video overlay and exporting merged media (photo+overlay or video+overlay).
    • Created a finger-drawing module for drawing curves on the screen and making sure that lines look as if a human had drawn it with pencil.
    • Ensured separation of concerns while writing a new feature. Ensured that the new feature is easily pluggable into the existing app.
    Technologies: iOS Instruments, Core Animation, Core Graphics, CocoaPods, Xcode, Objective-C, iOS
  • Mobile Software Developer Engineer

    2015 - 2016
    Dream Factory
    • Learned the Android platform and refreshed my Java skills.
    • Created mobile SDKs for NextUser (http://www.nextuser.com), a user tracking and eCommerce personalization tool (iOS and Android SDKs). Tasks included gathering requirements, writing tests, implementing features, and creating test builds. Published iOS SDK with Cocoapods.
    • Learned the Swift programming language.
    • Created a module in the existing Objective-C app for data sync between local database (Core Data) and remote database (MS Azure) needed for offline app usage.
    • Developed other iOS apps in Swift.
    Technologies: Android Studio, Java, Android, iOS Instruments, Xcode, Objective-C, Swift, iOS
  • iOS Software Developer Engineer

    2014 - 2015
    Real Networks
    • Developed RealTimes for iOS with Zagreb and Seattle teams (http://eu.real.com/mobile/apps.html).
    • Developed and designed lower-level features of the application such as network layer, auto-backup feature, sharing modules, location services module, video transcoding, etc., focusing on decoupling, modularity, and regular refactoring.
    • Created the auto-backup module for RealTimes, used for automatic uploads of photos and videos. Both foreground and background upload were supported. Additionally created a location-based module to wake up the application in intervals on significant location changes so that the uploads can be continued while ensuring that battery does not go empty because of the GPS tracking.
    • Extracted functionality of generating story-like videos from RealTimes into a separate SDK and helped integrate that SDK with other clients on-site in their offices.
    • Used Apple tools for profiling and detecting application bottlenecks (iOS Instruments).
    Technologies: iOS Instruments, Xcode, Objective-C, iOS
  • iOS Software Developer Engineer

    2012 - 2014
    Five Agency
    • Worked with a remote team as part of the outsourced local team with a nine-hour time difference and gained valuable experience working with a client remotely.
    • Learned Objective-C in depth and best practices for building mobile apps.
    • Used native iOS technologies and Agile programming methods.
    • Implemented modules with defined APIs which were used in Real Player Cloud for iOS (later rebranded to RealTimes).
    • Created modules for file upload and download which were used in the RealTimes iOS app for sharing of photos and videos with other devices and remote servers.
    • Collaborated with designers on best practices for developer-designer interactions.
    Technologies: iOS Instruments, Xcode, Objective-C, iOS


  • Looks Good

    It’s simple! When going somewhere and you want to look nice, your friends might not be around to help. Looks Good gives you access to fashionistas all over the world that want to help you look your best, instantly.

    Built the iOS app Looks Good from scratch in Objective-C. This was a side project which challenged me to bring UX/UI into the focus and making no compromises when implementing new features. Every UI transition and user action had to be polished and logical so that the app could feel "alive" while at the same time not going to crazy with animations so that they don't "take over" the purpose of user actions.

    App screencast video can be seen here: https://vimeo.com/189770810

  • Let Me In

    At an internal company hackathon at Fiveminutes, I developed a mobile application for unlocking office doors. The idea was that all of the people in an office can unlock the office doors when in the office's WiFi range. Used iOS/Android technologies and Arduino on the project. We were a team of three developers, and my job was to build mobile clients where I used Titanium SDK as a cross-platform solution. Mobile clients were communicating with Arduino over networks.

  • Swift Best Practices and Tips by Toptal Developers (Publication)
    This resource contains a collection of Swift best practices and Swift tips provided by our Toptal network members.
  • Swift Tutorial: An Introduction to the MVVM Design Pattern (Publication)
    On every new project, you have the privilege of deciding how you’ll architect the app and organize the code. But if you don’t pay attention, or you rush through coding, you risk ending up with spaghetti code. The solution? Use a proper design pattern. In this tutorial, Toptal Software Engineer Dino Bartošak explains how to implement an MVVM design pattern on a demo Swift application.


  • Languages

    Objective-C, Java, Swift, GraphQL
  • Frameworks

    UIKit, Cocoa Touch, AFNetworking, Core Data, StoreKit, RealmSwift, gRPC
  • Libraries/APIs

    Core Animation, Alamofire, Google Maps, CocoaPods, Facebook Pop, Facebook SDK, Core Graphics, RxSwift, Stripe, Firebase iOS SDK, Facebook Login
  • Tools

    Trello, Xcode, Interface Builder, iOS Instruments, Jira, Confluence, Auto Layout, Git, Crashlytics, TestFlight, Android Studio, Sketch, Figma
  • Paradigms

    Agile Software Development, REST, Object-oriented Programming (OOP), Model View Viewmodel (MVVM)
  • Platforms

    iOS, Amazon Web Services (AWS), Firebase, Android
  • Storage

    JSON, Amazon S3 (AWS S3)
  • Other

    Maps, Google Login, Analytics, AVFoundation, UI Animation


  • Master's Degree in Software Engineering and Information Systems
    2009 - 2012
    Faculty of Electrical Engineering and Computing - Zagreb, Croatia
  • Bachelor's Degree in Computer Science
    2006 - 2009
    Faculty of Electrical Engineering and Computing - Zagreb, Croatia

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