Ivo Leko, Developer in Split, Croatia
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Ivo Leko

Verified Expert  in Engineering

iOS Developer

Split, Croatia
Toptal Member Since
August 4, 2021

Ivo is an iOS software engineer and architect with 11 years of experience building native iPhone, iPad, and Apple Watch apps. He has programming experience with iOS SDK (Swift and Objective-C), Qt Symbian, C and C++, assembler, and web. His interest in science and technology encourages him to participate in inventing new concepts. Still, his greatest passions are programming, software architecture, algorithms, security, sensors, and animations that result in high-quality native iOS apps.


iOS SDK, Core Animation, Sensor Data, Core Motion, Maps, Neo4j...
Evolutio IT
iOS, WatchOS, Widgets, Socket.IO, Model View ViewModel (MVVM), Swift, Scrum...
Jealousy, Ltd.
Objective-C, Swift, Core Animation, Databases, Video Editing, Video Processing...




Preferred Environment

MacOS, iOS, Xcode, Slack, Zeplin, PAW, Git

The most amazing...

...project I’ve developed is an iOS framework for real-time magnet position detection. It became viral and was published on several popular tech blogs.

Work Experience

iOS Software Engineer and Architect

2014 - PRESENT
  • Invented and created a completely new way of interacting with a device using magnets.
  • Developed multiple apps for several clients in various industries like sports, tourism, food, shopping, entertainment, insurance, and more.
  • Became an early adopter of Kotlin Multiplatform Mobile in developing mobile apps with a shared codebase for business logic.
  • Created in-house apps for remote access to AWS S3 and Neo4j graph database.
Technologies: iOS SDK, Core Animation, Sensor Data, Core Motion, Maps, Neo4j, Amazon S3 (AWS S3), Kotlin Multiplatform Mobile (KMM), Swift, Kotlin, Augmented Reality (AR), Machine Learning, iOS SceneKit, Special Purpose Machines (SPM), Carthage, SnapKit, Trello, REST, Cocoa Touch

Team Lead iOS Developer

2018 - 2020
Evolutio IT
  • Solved stability and performance problems with current apps.
  • Refactored a sports betting iOS app with modern and custom-made MVVM architecture.
  • Created a modern approach for easy debugging and integration testing.
  • Led a team of five iOS developers through Jira and Scrum.
Technologies: iOS, WatchOS, Widgets, Socket.IO, Model View ViewModel (MVVM), Swift, Scrum, Jira, UI Testing, Integration Testing, Unit Testing, Git, Apple Push Notifications, Carthage, Bash Script, Alamofire, REST, iOS Native Libraries, Cocoa Touch, API Integration, APIs

Lead iOS Software Engineer and Architect

2016 - 2018
Jealousy, Ltd.
  • Created a new, fully functional social network from scratch.
  • Served as a lead iOS developer and system co-architect working on the product design.
  • Created an advanced video editing, cropping, and processing module with support for multi-pass encoding and GPU acceleration.
  • Invented and implemented the entire new navigation experience based on 3D Touch and Haptic Touch.
  • Developed fully custom UI animations on scrolling, screen opening, and other transitions.
Technologies: Objective-C, Swift, Core Animation, Databases, Video Editing, Video Processing, Video Encoding, Image Processing, Cropper, UIKit, Haptic Feedback, Git, Apple Push Notifications, ReactiveCocoa, REST

Senior iOS Developer

2015 - 2016
Sentegrity, LLC.
  • Worked on an advanced mobile authenticator that combines high-security data protection with a simple user experience.
  • Integrated the mobile authenticator into BlackBerry Enterprise (previously Good Technology) applications with industry-leading behavioral authentication that profiles the user and the device risk at the moment of access.
  • Detected user behavior based on current location, phone orientation, magnetic field, WiFi connections, Bluetooth connection, and more.
Technologies: Objective-C, Mobile Security, SSL Certificates, APIs, Obfuscation, Data Protection, Machine Learning, Core Motion, Core Location, Core Bluetooth, Encryption, iOS Native Libraries, Cocoa Touch

Senior iOS Developer

2014 - 2015
  • Developed in-house mobile solutions for International Medical Corps and Pretzel Crisps.
  • Led a team of four mobile app developers, both iOS and Android.
  • Worked with clients from all around world, namely the USA, United Kingdom, and Sweden.
Technologies: Objective-C, Swift, Core Animation, REST APIs, Maps, Core Location, Core Data, SQLite, Apple Push Notifications, Android, iPad, iOS, iPhone, CocoaPods, JSON API, Storyboarding, Cocoa Touch, API Integration, APIs

iOS Developer

2013 - 2014
  • Developed Codeanywhere iPhone and iPad apps from scratch.
  • Created a custom keyboard specially designed for programming on iOS devices.
  • Integrated a JavaScript web library for code highlighting inside a native iOS app (hybrid apps).
Technologies: Objective-C, iOS, iPad, iPhone, Core Animation, Core Graphics, Socket.IO, Hybrid Apps, Custom Keyboards, Automatic Reference Counting, CocoaPods, Cocoa Touch

Mobile App Developer

2010 - 2013
  • Developed the Croatian weather forecast app for Symbian OS (S60v3, S60v5, and Symbian^3).
  • Built a to-do list app for iPhone with a customizable interface and calendar sync, similar to Reminders.
  • Created the official Croatian Bible app for both iPhone and iPad with many features like marking, writing notes, bookmarks, diary, choosing custom font and theme, advanced search, social sharing, and more.
Technologies: Symbian, Objective-C, C++, Qt Creator, iPhone, iPad, UIKit, iOS SDK, Memory Management, Core Data, Calendars, HTML, CSS, JavaScript, XML


Jealousy is a social network with a completely different mindset and a new user experience (UX) never seen on mobile devices. The whole focus of our social network is to encourage users to publish quality content—This way, users won't be overloaded with useless and repetitive content. This concept allows new users to advance within the network and gain popularity more easily, without the need for the users to be popular in real life.

I owned the entire development of the iOS version of the app.

Tipster Sportwetten Version 2.0 to 4.0

A native sports betting app for iPhone with the fastest odds, live betting, cash-out, multi-bets and large payouts.

I led a team of iOS developers and we managed to completely refactor the app with modern MVVM architecture, which allows easy debugging and integration testing.

Real-time Magnet Position Detection with Smartphone | iPhone

This is my working concept and demonstration of a completely new way of interaction with the device. I created a framework for easy position and rotation detection of a neodym magnet using a single magnetometer that is built in every iPhone.


BioEncrypt is an open-source framework that balances mobile application security with usability. TrustScores are generated from over 30 behavioral biometric and device integrity data points to determine an authentication method proportionate to the risk. Trust measurements normalize security posture across devices and users, enabling consistent enforcement of security in diverse environments.

I am one of the contributors of this framework and the repository is available on GitHub.


SportEventz app provides TV and livestream sports schedules, broadcasting channel details for more than 25,000 sports matches in over 30 sports from more than 100 countries.

I led a team of iOS developers and we managed to create a stable app with a modern UI.

3D Menu

This is the implemented idea of a new app navigation experience using 3D (Force) Touch technology with no tabs nor side menus. Users just have to use hard pressure anywhere on the screen to call the new 3D Menu.

I am the co-author of this concept and the main developer for the iOS platform. If the device does not have 3D Touch support, long-press detection Haptic Touch is used instead.


Codeanywhere is a text, code and markup editor that has been redesigned and reengineered to be light, fast, and mobile-friendly. Users can connect to their FTP, SFTP servers, Dropbox, or GitHub accounts and easily manipulate the resources, folders, or files just with the swipe of their finger.

I created both the iPhone and iPad apps.


ILTranslucentView is a little open-source subclass of UIView that provides a native iOS 7 and blur, translucent effect. It can be used on all iOS devices in real time without any performance problems. It also supports smooth UIView animation of color, frame, alpha, and more.

I am the author and main contributor of this project that is publicly available on GitHub.

In-house App for Pretzel Crisps Company

This was designed both as an iPhone and iPad app for the company's employees to easily present their deals to the customers and facilitate their work. The app contains an augmented reality module (In-Store simulation) which enables users to snap camera images together with virtual racks.

I was the lead iOS programmer and architect while working in Profico company.

HR Biblija

The official Croatian Bible for iPhone and iPad released by Krscanska Sadasnjost. It comes with many features like marking, writing notes, bookmarks, diary, custom font and theme, advanced search, social sharing, and more. It is available since iOS 4. A bigger update with the new UI was released in September 2017.

I owned the entire development of this app.
2011 - 2013

Master's Degree in Computer Science

Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture (FESB) - Split, Croatia

2008 - 2011

Bachelor's Degree in Computer Science

Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture (FESB) - Split, Croatia


Core Animation, Core Graphics, JSON API, Alamofire, SnapKit, iOS Native Libraries, REST APIs, PAW, Socket.IO, Firebase iOS SDK, CocoaPods, GitHub API, Dropbox API, Facebook API, Instagram API, X (formerly Twitter) API, Google API


Xcode, Slack, Zeplin, Git, Jira, Apple Push Notifications, Grand Central Dispatch, Crashlytics, Firebase Cloud Messaging (FCM), Trello, Qt Creator, GitHub


Core Motion, Core Location, UIKit, iOS SDK, Cocoa Touch, Core Bluetooth, Core Data, iOS SceneKit, ReactiveCocoa


Swift, Objective-C, C++, Assembler, C, Kotlin, HTML, CSS, JavaScript, XML, Bash Script


Object-oriented Programming (OOP), Model View ViewModel (MVVM), Unit Testing, Scrum, REST


iOS, WatchOS, Firebase, Apple Watch, MacOS, Unix, Android, Symbian


Databases, JSON, SQLite, Neo4j, Amazon S3 (AWS S3)


Image Processing, Cropper, iPhone, Automatic Reference Counting, Memory Management, Sensor Data, Carthage, API Integration, APIs, Algorithms, Mobile Security, iPad, Maps, UI Testing, Integration Testing, Video Editing, Video Processing, Video Encoding, Haptic Feedback, SSL Certificates, Data Protection, Encryption, Custom Keyboards, Kotlin Multiplatform Mobile (KMM), Multithreading, Push Notifications, iOS Camera, Firebase Instance ID, Special Purpose Machines (SPM), In-app Purchases, Video & Audio Processing, Bluetooth, Machine Learning, Web Development, Widgets, Obfuscation, Hybrid Apps, Calendars, Siri, Background Jobs, WiFi, FTP, Augmented Reality (AR), Touch ID, Storyboarding, Deep Linking

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