This document discusses developing mobile apps using C++ for cross-platform code sharing. It outlines the benefits of using C++, including reduced development time and costs from sharing 70% of code across iOS, Android and desktop platforms. While C++ is well-suited for business logic and data layers, the document recommends choosing solid cross-platform libraries, defining clear interfaces between platforms, and starting simple to learn cross-platform development in C++.

1. Developing in C++ for Mobile
Igor Kantor
CTO @

2. С++ in mobile

3. Our case
• Product: iOS, Android Apps; Backend; Desktop coming
• Communication protocol; API; security; client-server
• A lot of non-trivial code to be duplicated
Android
iOS
Symbian
The whole solution brakes down, because somethings
takes too much time to implement on Android

4. Why should we re-write the same code
and fix the same bugs 2-3 times?

5. Goals
1. Less developers, optimize efforts, cost saving
2. Streamline and speed up the development and bugfixing
3. Increase stability and quality of the product

6. Option 1: cross-platform tools
• PhoneGap
• RhoMobile
• Sencha Touch
• appMobi
• Telerik
• Adobe AIR
• Xamarin
• Appcelerator Titanium
• Corona
• JavaScript

7. Option2: C++
OK, it’s clear with games. But what about business apps?

8. Decision
In 2013 we decided to re-design the product architecture and write the
core in C++
OS abstraction layer
Protocol Media
High-level SDK: business login, etc.
iOS
Android
Desktop
JNI
Symbian
C++
More to come

10. Our results
• Learning curve
• Are we happy? Definitely yes: 70% of code is shared in C++ and
support is much easier
• Streamlined development: we get all the new features
simultaneously

11. Lesson Learned
• Choose solid and convenient OS abstraction library
• We had to re-write timers routine 3 times!
• Encapsulation and polymorphism
• Understand what should remain native
• Unless 100% sure keep the networking part native
• Get a tool for interface between native language and C++

12. Recommendations

13. When to use
Use Don’t use
Long running project/product Short projects, outsourcing
Cost and effort optimization is a
key
Projects are not so complicated
Familiar and ready for C++ and
cross-platform C++ libraries
Don’t have enough C++ expertise

14. Embrace C++11/14
C++11/14 makes replacing ObjC/Java feasible:
• shared_ptr, unique_ptr
• new containers
• atomics and threading

15. Define where to put the line
• UI – not a good candidate for C++
• Business logic, Data, Model – perfect candidates
• Define what should remain native: e.g. networking

16. Choose solid OS abstraction library
• Choose it carefully
• Choose mature only solutions
• It will become your framework to provide you with primitives like
Thread, Timer, File access, etc. etc.
• Options: Qt, Boost, Poco, self-made

17. Interface
• Define how your Apps will speak to C++ part
• Think this through at the very beginning
• Easy on iOS; relatively easy on Windows (directly or PInvoke)
• JNI – default NDK option for Android. Try to avoid it.

18. Interface: options
Possible ways to build interfaces:
1. Traditional:
ObjC ↔ C++
Java ↔ JNI ↔ C++
2. Protocol Buffers + ZeroMQ
3. Djinni
4. http://google.github.io/flatbuffers/

19. Interface: Protocol Buffers + ZeroMQ
Benefits:
1. Your C++ part will act as “local server”
2. Thread safe
3. Language independent interface: don’t
have to define bindings and types for each
platform

20. Setup build/run process
• Be ready to test your code on Android/iOS which implies in having
both Desktop and Mac

21. Data layer
• A good candidate for cross-platform C++ implementation
• Many great libraries exists: SQLite, SQLCipher, Realm.io / Poco
• For simple structures use plain SQLite C implementation

22. Where to start
https://github.com/libmx3/mx3
Start with simple
prototypes just to get the
feeling on timers, threads,
data access, network, etc.

23. We’re in good company

24. Thank you
ihor.kantor@gmail.com