Janusz Gregorczyk, Developer in Szczecin, Poland
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Janusz Gregorczyk

Verified Expert  in Engineering

Software Developer

Location
Szczecin, Poland
Toptal Member Since
August 20, 2014

Janusz is an experienced iOS developer who has developed more than 40 iOS apps from scratch over the last few years while working on many more. Before that, he was a co-founder of Gameleons (in its prime time, one of Poland's biggest mobile development teams) and worked on over 50 mobile Java games.

Portfolio

Doist
Swift, iOS
codesize
Cocos2d, OpenGL, Instruments, UIKit, Git, iOS SDK, Objective-C
Bright Mediums
Multithreading, Core Data, iOS SDK, Objective-C

Experience

Availability

Part-time

Preferred Environment

Git, Xcode

The most amazing...

...thing I've coded was a Doom-style game engine in mobile Java.

Work Experience

iOS Developer

2014 - PRESENT
Doist
  • Developing iOS apps in Swift.
Technologies: Swift, iOS

Independent software developer (self-employed)

2008 - PRESENT
codesize
  • Worked remotely with businesses worldwide.
  • Specialized in mobile application development, particularly the iOS platform.
  • Developed about 40 iOS applications from scratch and worked on many more.
Technologies: Cocos2d, OpenGL, Instruments, UIKit, Git, iOS SDK, Objective-C

Senior iOS Engineer

2013 - 2014
Bright Mediums
  • Developed and maintained of several challenging iOS projects.
  • Worked in an Agile team.
  • Provided expertise in multithreaded CoreData, CoreLocation, UIKit.
Technologies: Multithreading, Core Data, iOS SDK, Objective-C

Senior iOS Developer

2013 - 2014
AppwoRx LLC
  • Worked on a 2.0 version and subsequent enhancements of a clinical photography application.
  • Almost completely rewrote the iOS code base, developing an iOS universal application, heavily interfacing with a REST-ful back end.
Technologies: REST, Interface Builder, CocoaPods, iOS SDK, Objective-C

Mobile Hero

2010 - 2013
Brothers Media
  • Developed several beautifully designed iOS universal applications featuring in-app purchases, maps, and push notifications.
Technologies: In-app Purchases, MapKit, Core Location, Core Animation, UIKit, Objective-C

CTO, Co-founder

2005 - 2008
Gameleons Sp. z o.o.
  • Managed development and R&D activities of one of Poland's top mobile game studios of the time.
  • Involved in over 40 J2ME projects, from conception to post-production maintenance.
  • Developed several game engines, a local Bluetooth multiplayer solution, and a core porting technology.
Technologies: Continuous Integration (CI), Python, Java, J2ME

C/C++ Programmer / Contractor

2003 - 2004
InterActive Vision Mind Beacon Sp. z o.o.
  • Helped port two arcade simulator games from PC to the PlayStation 2 platform: Operation Air Assault and Pacific Warriors 2.
  • Worked on platform and compiler porting of large Visual C++ code base to PS2 and GCC.
  • Implemented PS2-specific features.
  • Performed subsequent optimization and bug fixing.
Technologies: Subversion (SVN), RenderWare, PlayStation, GCC, Microsoft Visual C++, C++, C

C/C++ Programmer

2001 - 2003
InterActive Vision Mind Beacon Sp. z o.o.
  • Programmed a variety of applications on Palm OS and Windows Mobile.
  • Developed game back end, parts of user interface and various other components of the PC game Airlines 2.
Technologies: Subversion (SVN), Palm OS, WinAPI, Microsoft Visual C++, C++, C

Zonnesimulator for Eneco

Solar panel planner / calculator for an international sustainable energy company.

I worked on UIDocument-based renewable energy calculator and used complex CoreAnimation transforms.

RxPhoto for AppWorks LLC

http://myappworx.com/rxphoto/
I was responsible for the 2.0 release of this clinical photography application. It was an almost-total rewrite of the iOS codebase, developing an iOS universal application heavily interfacing with a REST-ful backend.

Ahold Experience for Ahold Europe

Corporate training/gamification app.

Used Vuforia SDK, OpenGL, and AVFoundation for AR video display.

The Bovenkant van Nederland for Scriptum Publishers

Aerial photography album.

Developed a custom interface with lots of CoreAnimation, MapKit, IAPs, CoreLocation.

Dinosaurs for Kids for Potrus Publishing Sp. z o.o.

Interactive book based on custom OpenGLES/C++ engine with Lua and Box2D.

Languages

C, Objective-C, C++, JavaScript, Python, Java, C#, Swift

Frameworks

ZURB Foundation, UIKit, Cocoa, AFNetworking, Core Data, Cocos2d, iOS SDK, Core Location, MapKit

Platforms

iOS, J2ME, PlayStation, Android

Libraries/APIs

Core Animation, Parse SDK, CocoaPods, OpenGL, WinAPI

Tools

Instruments, Interface Builder, Microsoft Visual C++, GCC, Subversion (SVN), Bitbucket, GitHub, Git, TextWrangler, Xcode

Paradigms

Continuous Integration (CI), REST

Other

Multithreading, In-app Purchases, RenderWare, Palm OS, AVFoundation

1999 - 2004

MSc Degree in Electronics Engineering

Zachodniopomorski Uniwersytet Technologiczny w Szczecinie - Szczecin, Poland

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