Techniques for Cross Platform .NET Development

Jeremy Hutchinson@hutchcodes

What is “Cross Platform”

Android PhoneAndroid TabletAndroid Wear

iPhoneiPad

Apple WatchApple TV

Windows PhoneWindows AppsMicrosoft Band

SilverlightXBox

.Net Core.Net (ASP, WPF, Winforms, Etc)

Supported Languages and Tools

Shared Logic

Platform A Platform B

using Windows.Storage;namespace XPlat{ public class UserData      {      public List<TodoItem> GetUserTodoList()     {          var userName = this.UserName;          //Make a call to a cloud resource     }     public string UserName     {         get         {             return ApplicationData.Current.LocalSettings.Values["UserName"].ToString();         }         set         {             ApplicationData.Current.LocalSettings.Values["UserName"] = value;         }     } }}

Linked Files Shared Project* Portable Class

Conditional Compile Partial Classes Inheritance Dependency Injection

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Linked Files

Shared Projects

UserData.cs

WinPhone8 Project Windows81 Project

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using System.IO.IsolatedStorage;namespace XPlat{ public class UserData      {      public List<TodoItem> GetUserTodoList()     {          var userName = this.UserName;          //Make a call to a cloud resource     }     public string UserName     {         get         {             return IsolatedStorageSettings.ApplicationSettings["UserName"].ToString();         }         set         {              IsolatedStorageSettings.ApplicationSettings["UserName"] = value;         }     } }}

Conditional Compilation#if DEBUG    public string Foo; #else     public string bar; #endif

Conditional Compilation

#if SILVERLIGHT using System.IO.IsolatedStorage; #else using Windows.Storage; #endif namespace XPlat {     public class UserData     {         public string UserName         {             get             { #if SILVERLIGHT                 return IsolatedStorageSettings.ApplicationSettings["UserName"].ToString(); #else                 return ApplicationData.Current.LocalSettings.Values["UserName"].ToString(); #endif             }

#if SILVERLIGHT using System.IO.IsolatedStorage; #else using Windows.Storage; #endif namespace XPlat {     public class UserData     {         public string UserName         {             get             { #if SILVERLIGHT                 return IsolatedStorageSettings.ApplicationSettings["UserName"].ToString(); #else                 return ApplicationData.Current.LocalSettings.Values["UserName"].ToString();#endif             }             

#if SILVERLIGHT using System.IO.IsolatedStorage; #endif#if NETFX_COREusing Windows.Storage; #endif #if __IOS__using Foundation; #endif #if ANDROIDusing Android.App;using Android.Content; #endif

Partial Classes

namespace XPlat {     public partial class UserData     {         public List<TodoItem> GetUserTodoList()         {             //Get the username for local storage             var userName = this.UserName;             //Make a call to a cloud resource         }     } }

using Windows.Storage;namespace XPlat{ public partial class UserData      {     public string UserName     {         get         {             return ApplicationData.Current.LocalSettings.Values["UserName"].ToString();         }         set         {             ApplicationData.Current.LocalSettings.Values["UserName"] = value;         }     } }}

using System.IO.IsolatedStorage;namespace XPlat{ public partial class UserData      {     public string UserName     {         get         {             return IsolatedStorageSettings.ApplicationSettings["UserName"].ToString();         }         set         {              IsolatedStorageSettings.ApplicationSettings["UserName"] = value;         }     } }}

Inheritance

namespace XPlat {     public abstract class UserDataBase     {         public List<TodoItem> GetUserTodoList()         {             //Get the username for local storage             var userName = this.UserName;             //Make a call to a cloud resource         }         public abstract string UserName { get; set; }     } }

using Android.App; using Android.Content; namespace XPlat {     public class UserData : UserDataBase    {        private readonly ISharedPreferences _preferences;        public UserData()        {            var ctx = Application.Context;            _preferences = ctx.GetSharedPreferences(ctx.PackageName, FileCreationMode.Private);        }        public override string UserName        {            get { return _preferences.GetString("UserName", ""); }            set            {                using (var editor = _preferences.Edit())                {                    editor.PutString("UserName", value);                    editor.Commit();                }            }        }    }}

What do all these have in common?namespace XPlat

var userData = new XPlat.UserData();var todos = userData.GetUserTodoList();

Dependency Injection

namespace XPlat {    public interface IStoredSettings    {        string UserName { get; set; }    } }

namespace XPlat {    public class UserData    {        private readonly IStoredSettings _storedSettings;        public UserData(IStoredSettings storedSettings)        {            _storedSettings = storedSettings;        }        public List<TodoItem> GetUserTodoList()        {            //Get the username for local storage            var userName = _storedSettings.UserName;            //Make a call to a cloud resource            throw new NotImplementedException();        }    }}

using Foundation; namespace XPlat.iOS {    public class AppleSettings : IStoredSettings    {        public string UserName        {            get { return NSUserDefaults.StandardUserDefaults.StringForKey("UserName"); }            set            {                var defaults = NSUserDefaults.StandardUserDefaults;                defaults.SetString(value, "UserName");                defaults.Synchronize();            }        }    }}

var userData = new XPlat.UserData(new XPlat.iOS.AppleSettings());var todos = userData.GetUserTodoList();

Linked Files Shared Project* Portable Class

Conditional Compile Partial Classes Inheritance Dependency Injection

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Manage Platform

Differences

How do we share code?

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