Cross platform mobile apps using .NET
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The document discusses techniques for developing cross-platform mobile applications using .NET, highlighting eight specific methods including portable class libraries and leveraging MVVM patterns. It addresses the importance of code reuse and maintenance challenges when developing for multiple platforms, and provides examples and demos to illustrate the techniques. Additionally, it offers links to resources and a complete tutorial for creating an app compatible with iOS, Android, and Windows Phone.
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Cross platform mobile apps using .NET
- 1. Cross platform mobile apps using .NETJonas FollesøNDC, June 2011
- 2. AGENDA:Why?
- 3. 8 techniques
- 7. TILE FLOOD
- 8. TILE FLOOD
- 11. REUSE SKILL SET?
- 12. REUSE CODE?privatevoidopen_Click(objectsender, RoutedEventArgse){varchannel=HttpNotificationChannel.Find("NNUG");if (channel==null) {channel=newHttpNotificationChannel("NNUG"); }channel.ChannelUriUpdated+=channel_ChannelUriUpdated;channel.ShellToastNotificationReceived+=channel_ShellToastNotificationReceived;channel.Open();}
- 13. REUSE LIBRARIES+35 libraries monotouch.info/MonoTouch/LibrariesCOST OF MAINTAINING MULTIPLE CODE BASES
- 14. LIKE C#..?
- 15. ... OR DISLIKE THE ALTERNATIVE
- 16. OBJECTIVE-C: DATE (NO TIME)+ (NSDate *) stripTime:(NSDate *) date {NSCalendar *gregorian = [[NSCalendaralloc] initWithCalendarIdentifier:NSGregorianCalendar];NSDateComponents *components = [gregorian components: (NSYearCalendarUnit | NSMonthCalendarUnit |NSDayCalendarUnit)fromDate:date]; date = [gregoriandateFromComponents:components]; [gregorian release]; return date;}
- 17. C#: DATE (NO TIME)public DateTimeStripTime(DateTime date){ return date.Date;}
- 19. TECHNIQUE 1:PORTABLE CLASS LIBRARY
- 20. HELP YOU STICK TO A COMMON SUBSET
- 21. PORTABLE CLASS LIBRARYPROSOne class library for all platforms
- 22. Helps you stick to a common subsetCONSNo Preprocessor Directives
- 23. No Platform Specific Code in Class Lib
- 24. Not directly supported on MonoDevelop yetTECHNIQUE 2:LINKED FILES
- 26. LINKED FILESPROSSame code across all platforms
- 27. Ability to add platform specific code
- 28. Preprocessor DirectivesCONSNeed to manage multiple projectsTECHNIQUE 3:LINK FILES USING «PROJECT LINKER»
- 29. PROJECT LINKERPROSAuto link files between projectsCONSDoes not work in MonoDevelop
- 30. Must have all projects in same solutionTECHNIQUE 4:VSMonoTouch Open MonoTouch projects in VS2010
- 31. VSMonoTouchPROSOpen and build (verify) MonoTouch in VS2010CONSNot a «real» build
- 32. Some manual steps involvedTECHNIQUE 5:PREPROCESSOR DIRECTIVES
- 33. using System.Net;#if MONOTOUCH || MONODROIDusing System.Web;#endif
- 34. PREPROCESSOR DIRECTIVESPROSEasily write platform specific codeCONSCode smell
- 35. DRY – The #ifdefs tend to spreaddemo
- 38. // Windows Phone 7publicclassDispatchAdapter : IDispatchOnUIThread{publicvoid Invoke(Action action) {Deployment.Current.Dispatcher.BeginInvoke(action); }}
- 39. // Mono for AndroidpublicclassDispatchAdapter : IDispatchOnUIThread{privatereadonlyActivity _owner;public DispatchAdapter(Activity owner) { _owner = owner; }publicvoid Invoke(Action action) { _owner.RunOnUiThread(action); }}
- 40. // MonotouchpublicclassDispatchAdapter : IDispatchOnUIThread{ privatereadonly NSObject _owner; publicDispatchAdapter(NSObject owner) { _owner = owner; } publicvoid Invoke (Action action) { _owner.BeginInvokeOnMainThread(newNSAction(action));}}
- 41. ABSTRACT FUNCTIONALITYPROSShare even more code
- 42. Do not need preprocessor directivesCONSMore abstractions in codeTECHNIQUE 7:LEVERAGE MVVM ON ALL PLATFORMS
- 43. Ensure that any code that manipulates presentation only manipulates presentation, pushing all domain and data source logic into clearly separated areas of the program.Martin Fowler, Separated Presentation, July 2006
- 46. Data & Domain Logic(Model)UI(View)Interaction (Controller/Presenter)
- 47. MVVMPATTERN FOR BINDABLE UI
- 48. APP LOGIC IN CODE BEHIND IS HARD TO TEST AND MAINTAINVIEWXAMLDataModelCode-BehindEventHandlers
- 49. SEPARATE USINGMVVMVIEWXAMLCode-BehindChange notificationData-binding and commandsVIEW MODELData ModelState + Operations
- 50. publicclassObservableAdapter<T> : BaseAdapter<T>{privatereadonlyActivity _context;privatereadonlyObservableCollection<T> _collection;publicObservableAdapter(Activitycontext, ObservableCollection<T> collection) { _context = context; _collection = collection; _collection.CollectionChanged += (o, e) => NotifyDataSetChanged();}...ListAdapter = newObservableAdapter<Airport> (this, _viewModel.Airports);
- 51. publicabstractclassObservableDataSource<T> : UITableViewDataSource{ publicObservableDataSource (ObservableCollection<T> collection, UITableView tableView) { _tableView = tableView; _collection = collection; _collection.CollectionChanged += (o, e) => { tableView.ReloadData(); }; }...
- 52. APPLYING MVVMPROSShare even more code
- 53. Testable View ModelsCONSMore abstractions in code
- 54. May not feel natural to platformdemo
- 55. TECHNIQUE 8:USE PRE-BUILT ABSTRACTIONS
- 58. Camera
- 59. Compass
- 60. Geolocation
- 61. Notification
- 62. Storage
- 63. Contacts
- 65. One common API for phone specific functionality across all three devices
- 66. Inspired by PhoneGap(same API)http://www.flickr.com/photos/tambako/3974809361/
- 67. privatevoid FindNearestAirport(){var coordinates = new MonoMobile.Extensions.Geolocation(); coordinates.GetCurrentPosition(PositionAvailable);}privatevoid PositionAvailable(Position position){Console.WriteLine("{0} {1}", position.Coords.Latitude, position.Coords.Longitude);}
- 68. privatevoid FindNearestAirport(){var coordinates = newMonoMobile.Extensions.Geolocation(); coordinates.GetCurrentPosition(PositionAvailable);}privatevoid PositionAvailable(Position position){Console.WriteLine("{0} {1}", position.Coords.Latitude, position.Coords.Longitude);}
- 69. 3x MonoMobile.Extensions.dllMonoDroid -> MonoMobile.Extensions.dll
- 73. Windows Phone 7 -> MonoMobile.Extensions.dll
- 74. Implemented using GeoLocationWatcherABSTRACT FUNCTIONALITYPROSShare even more code
- 75. Same set of abstractions used in multiple apps
- 76. Well known APICONSMore abstractions in code
- 77. Smallest common denominatorDOES IT WORK IN PRACTICE?http://www.flickr.com/photos/kozloski/2306510520/
- 78. FLIGHTS NORWAYMONITORARRIVALS AND DEPARTUREShttp://www.flickr.com/photos/svenwerk/2181849280/
- 80. demo
- 81. SUMMARYPortable LibraryLinked FilesProject LinkerVSMonoTouchPreprocessor DirectivesAbstracting Common FunctionalityLeverage MVVMUsing Pre-built Abstractions
- 82. FORK ME ON GITHUBgithub.com/follesoe/FlightsNorwayComplete app for iOS, Android & WP7
- 83. 56 page tutorial with step-by-step code.Jonas FollesøScientist+47 977 [email protected]@follesoe.no