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Igor Ostriz, iOS Developer in Zaprešić, Croatia
Igor Ostriz

iOS Developer in Zaprešić, Croatia

Member since April 26, 2012
Igor is a top full-stack developer focusing on iOS over the past eight years. Most of his experience is on building UX, but he also values real-time-communication technologies He has several more years of experience programming fault-tolerant systems (for telecoms). He has worked with a broad range of technologies and team sizes, and he has also taken lead roles as a developer or system architect.
Igor is now available for hire



  • C++, 13 years
  • iOS, 10 years
  • Objective-C, 8 years
  • Swift, 4 years
  • JavaScript, 4 years
  • XMPP, 3 years
  • Node.js, 2 years
  • React Native, 1 year
Zaprešić, Croatia



Preferred Environment

Xcode, VSCode

The most amazing...

...thing I've built is Touchmoon Messenger.


  • Lead iOS Developer

    2018 - 2019
    • Built a Swift application that renders articles distributed from a server contained in XML and JSON data. In a short time, the app acquired over 750 thousand active users worldwide.
    • Developed the data and UI to be available in 80+ languages, switchable in real time so that app functionality can run independently of the system language.
    • Adapted Swift to be used with its dynamic features to accommodate dynamic data structures that describe UX and data.
    • Used XCTest framework for checking some precondition states and preventing easily detectable failures.
    Technologies: Swift, RealmSwift, PromiseKit, AlamoFire, Google Analytics
  • Lead iOS Developer/Architect

    2018 - 2018
    Mateflick Photobank
    • Led the development of an app that connects professional photographers with their clients. Photographers can take photographs at fairs and approach clients with targeted photos. The client can easily download and preview photos from that photographer and later buy full digital version of selected photos.
    • Built a money exchange ecosystem to support the app.
    Technologies: Swift, MongoDB, Facebook SDK, Instagram SDK, AVFoundation
  • Lead Developer and Acting CEO

    2014 - 2018
    Touchmoon, Inc.
    • Developed a full-blown platform for sharing emotions (yes, even messages). It has a ton of unique features, including localized content, custom games, animations, and solid security practices.
    • Included WebRTC for voice/video chat via WebRTC framework. It was a challenge to implement it due to a short timeframe required to push it out. We have built two main back-end services, one REST API that resides on Node, and another on Ejabberd (yes, it required a bit of Erlang).
    Technologies: iOS, WebRTC, Node.js, Ejabberd
  • Lead Developer

    2015 - 2015
    • Utilized Parse and created back-end software in PHP to help develop an app for peer coaching among young people.
    • Created interesting animations and UX style.
    Technologies: iOS, Parse
  • Lead iOS developer, System Architect

    2014 - 2015
    • Led the development of Classkick. Designed as a classroom helper tool, this the best iPad app for this task. Teacher can prepare lecture, deliver tasks and watch everyones screen for the progress.
    Technologies: Objective-C, Firebase
  • Lead iOS Developer

    2013 - 2013
    StalkDocs (via Toptal)
    • Built an application for sales representatives that helps them share information among themselves and differentiate between private and public information.
    • Created the back end on Parse and integrated Apple and Stripe payment processes.
    Technologies: Objective-C, Parse, JavaScript
  • iOS Developer

    2012 - 2013
    Chromatic (via Toptal)
    • Developed the back end using Node.js and MongoDB, using CoffeeScript.
    • Built the client for web and iPad.
    Technologies: Objective-C, CoffeeScript
  • Lead iOS Developer

    2012 - 2013
    Pictrition (via Toptal)
    • Customized the GUI, targeted mainly for iOS6, with lots of beautiful graphics, charts, photos, and more.
    • Integrated with Facebook and Twitter, making it essentially social gaming with awards.
    • Developed the back end with Sinatra Ruby hanging on MongoDB.
    • Hosted with Heroku, MongoHQ, and Cloudinary for pictures.
    Technologies: Objective-C
  • iOS Developer

    2012 - 2012
    NDA (via Toptal)
    • Built for a popular notebook application on the iPad. The request was to develop a wrist protection area that could be freely sized, for the purpose of protecting the drawing canvas from unwanted wrist touches while painting on a screen.
    • Developed zoom control that would enable drawing (mostly writing with finger or stylus) on an enlarged area located on the wrist guard that represents a small portion of the line on a notebook paper. Included automatic movement of a satellite (small portion on the paper) to the right while writing, advancing to the next row, scrolling of paper canvas, snapping to the predefined rows for easy positioning, and more.
    • Tested several approaches during the development of this project: OpenGLES 1 and 2, touch event forwarding (unfortunately achievable only by private API).
    • Used a plain Quartz drawing subsystem for zooming. Similar applications were studied during this process (Noteshelf, Notabillity). The result is comparable/better than competitive products.
    Technologies: Objective-C, OpenGLES 2
  • iOS Developer

    2012 - 2012
    Circa (via Toptal)
    • Developed custom page curl animation without using Apple private API that would prevent successful app submission to the App Store.
    • Achieved 60fps curl animation to allow for a great UX.
    • Built a small library that would curl any UIView, and that view remained interactive during curling.
    • Overrode a couple long-standing and publicly known issues with iOS (e.g., CADisplayLink mysteriously drops fps to 40).
    Technologies: Objective-C, OpenGLES 2
  • Lead Developer

    2012 - 2012
    Bitmoji/Future Instruments (via Toptal)
    • Developed a proof-of-concept/demo for Slidewall application.
    • Used Slidewall as an interactive projection of photos, videos and notes called Slideas. Slideas are displayed and organized on the SlideWall by a team or group of people to create, edit and share ideas in real-time from anywhere utilizing Cloud technologies.
    Technologies: Java (, Objective-C, Python
  • ASP MVC Developer

    2011 - 2012
    Hamilton Fraser Insurance Company (UK)
    • Developed complex online management of tenancy deposits (used by landlords, tenants, and agencies), support of online payments, property data management, dispute resolution, complex reporting, importing of property and tenancy external data, complex queries and administrative tasks, and payment detection through parsing of banking data exchange formats.
    Technologies: C#
  • Lead Developer

    2009 - 2010
    ANPR Parking System
    • Built a parking management system with plate recognition. The system consists of entry/exit IP cameras that constantly broadcast an image to the central server. Server detects motion in particular part of the image and reads plate (OCR). Based on data the ramp automatically rises (or not).
    • Architected the project and led a five-person development team.
    Technologies: ASP.NET, REST, XML, JSON, MS SQL
  • Lead Developer

    2008 - 2009
    DZNS - NMS
    • Created a management system for the Croatian State Office for Nuclear Security (DZNS). The server collects data from all radiologic stations throughout the country. Comparing results to the acceptable thresholds, and alerting if attention is needed.
    • Used a web server as the presentation layer.
    • Led a three-person development team.
    Technologies: Python, Django HTML, JavaScript
  • Lead Developer

    2008 - 2008
    Offline Charging
    • Developed mediation for offline charging (for the largest Telco operator in Croatia, T-Com), collecting customer data record (CDR) data from the Diameter server, and preparing them for further analysis.
    • Led development in a team of three.
    Technologies: Python
  • Lead Developer

    2005 - 2007
    OT Viewer
    • Created CDR BI for one of our telco operators (Optima Telecom d.o.o.). The platform consists of a server application (data retrieval from the DW – Oracle 9i) and client application for viewing, analyzing, summarizing, and printing bills as a convenience GUI app for end users.
    • Distributed the client application to the clients/customers of Optima Telecom.
    • Led architecture and development in a team of five.
    Technologies: Python, Oralce9i, C++, MFC/BCG
  • Web Developer

    2005 - 2005
    • Conducted risk assessment analysis for INA Naftaplin (the largest oil company in Croatia).
    • Developed the system in cooperation with the University (FER) and Enconet d.o.o. Involved three risk assessment methodologies: What-If, FMEA, and HAZOP.
    • Led a development of team of three.
    Technologies: VB6, C#


  • Classkick (Development)

    A great app to help teachers communicate with students in a fun way. The teacher monitors work in real time via an iPad interface, and students can get immediate attention by raising a virtual hand. I was involved as a system architect and a lead developer in a team of six, working with the Firebase-based back end.


  • Languages

    Swift, C, Objective-C, C#, C++, Ruby, Python, Visual Basic, JavaScript, Erlang
  • Frameworks

    XMPPFramework, Cocoa, Boost, Cocos2d, React Native, Ruby on Rails (RoR)
  • Libraries/APIs

    WTL, OpenGL, WebRTC, Node.js
  • Tools

    Xcode, InstallShield, Adobe Photoshop
  • Paradigms

    Mobile Development, Functional Programming, Concurrent Programming, Agile Software Development
  • Platforms

    Visual Studio Code, MacOS, iOS, Apple, Windows, Android
  • Other

    CTO, Windows Presentation Foundation (WPF), XMPP, Ejabberd, BCG
  • Storage

    MongoDB, PostgreSQL, SQLite, Microsoft SQL Server


  • Master's degree in Computer Science
    1993 - 1993
    University of Zagreb - Zagreb, Croatia
  • Masters degree in Compute Engineering
    1987 - 1992
    Faculty of Electrical Engineering and Computing, Zagreb, Croatia
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