Cross Platform Development in C# (DDDNorth 2013)
- 1. Cross Platform Mobile Development in C# Ross Dargan @rossdargan
- 2. What I’m going to cover Target 95% of the UK mobile market in C# With maximum code re-use
- 3. What I’m going to cover
- 4. What I won’t cover The other cross platform options (http://propertycross.com/) A full walkthrough of the tooling Blackberry
- 5. Android 56% Windows 12% iOS 27% Blackberry 4% Other 1% Other 5% UK Smartphone Landscape Source: http://bit.ly/19d2thf
- 6. Native Development iOS Objective C Xcode Windows Phone C#/Visual Basic/F# Visual Studio Android Java Eclipse IntelliJ
- 7. Xamarin • C# and .NET for Android, iOS and Mac • Full native APIs
- 8. The bad… • Price $2000 per dev per year • Still need a mac • Write once, run (and test!) everywhere • Tooling is still a bit immature (but the support is great!) • Need to write each UI separately
- 10. DEMO Hello World
- 11. So… Sharing
- 13. File Linking
- 15. File Linking Pros • Quick Cons • Messy code • Progressively more difficult to maintain as you add implementations • Very hard to test • File linking is a PITA to remember as you add files
- 16. SHARING CODE Portable Class Libraries
- 17. Adding a PCL
- 18. Great… but Still need platform specific code somehow…
- 22. Abstract Classes Pros • Quick • Easier to maintain • Follows Open/Closed principal Cons • Difficult to test • Pretty inflexible
- 24. Dependency Injection • Helps separate code (Single responsibility) • Allows you to unit test’s discrete parts of the implementation – no God classes • You can inject in platform specific implementations • Inversion of Control allows you to swap implementations easily
- 25. DEMO PCL & DI demo
- 26. Dependency Injection Pros • Very loosely coupled code (reuse) • Unit tests are easy • Single Responsibility • Open/Closed Cons • • •
- 29. What are the downsides to using Dependency Injection? It can be dangerous for your career because it may increase your overall knowledge of good API design. Once you learn how proper loosely coupled code can look like, it may turn out that you will have to decline lots of job offers because you would otherwise have to work with tightly coupled legacy apps. Happens to me a lot :) Source: http://bit.ly/com6aD
- 30. Dependency Injection Pros • Very loosely coupled code (reuse) • Unit tests are easy • Single Responsibility • Open/Closed Cons • More code • Bloated constructors
- 32. Can we squeeze any more reuse out?
- 33. MAXIMIZE UI CODE REUSE MVVM
- 34. MVVM Platform Specific Code Shared Code
- 35. Demo
- 36. Improving Code Reuse in 3 easy ways • Heavy use of dependency injection – Allows different implementations for different platforms • Use PCLs (and file linking for the time being) • Use View Models to reuse presentation code
- 37. 3 layers of win MVVMCross Xamarin Visual Studio
- 38. Links • http://xamarin.com/ • http://mvvmcross.wordpress.com/ • http://propertycross.com/ • https://github.com/rossdargan/Talks • Dependency Injection in .Net by Mark Seemann (ISBN: 1-935182-50-1) • http://www.icndb.com/api/
- 39. Questions