C#6 & MvvmCross Martijn van Dijk @mhvdijk [email protected] github.com/martijn00 speakerdeck.com/martijn00 

Agenda ■ C# 6 explained ■ What is MvvmCross 

Do you C# ??? Otherwise you would need some glasses 

C# 6 ■ C# 6 is the version of C# that ships with VS 2015. ■ The philosophy behind this version is straightforward: improve simple everyday coding scenarios, without adding much conceptual baggage. ■ The features should make code lighter without making the language heavier. 

Auto-property enhancements ■ Initializers for auto-properties public class Customer { public string First { get; set; } = "Jane"; public string Last { get; set; } = "Doe"; } 

Auto-property enhancements ■ Getter-only auto-properties public class Customer { public string First { get; } = "Jane"; public string Last { get; } = "Doe"; } public class Customer { public string Name { get; } public Customer(string first, string last) { Name = first + " " + last; } } 

Expression-bodied function members ■ Expression bodies on method-like members public Point Move(int dx, int dy) => new Point(x + dx, y + dy); public static Complex operator +(Complex a, Complex b) => a.Add(b); public static implicit operator string(Person p) => p.First + " " + p.Last; public void Print() => Console.WriteLine(First + " " + Last); 

Expression-bodied function members ■ Expression bodies on property-like function members public string Name => First + " " + Last; public Customer this[long id] => store.LookupCustomer(id); 

Using static using static System.Console; using static System.Math; using static System.DayOfWeek; class Program { static void Main() { WriteLine(Sqrt(3*3 + 4*4)); WriteLine(Friday - Monday); } } 

Extension methods using static System.Linq.Enumerable; // The type, not the namespace class Program { static void Main() { var range = Range(5, 17); // Ok: not extension var odd = Where(range, i => i % 2 == 1); // Error, not in scope var even = range.Where(i => i % 2 == 0); // Ok } } 

Null-conditional operators int? length = customers?.Length; // null if customers is null Customer first = customers?[0]; // null if customers is null int length = customers?.Length ?? 0; // 0 if customers is null int? first = customers?[0].Orders.Count(); // new int? first = (customers != null) ? customers[0].Orders.Count() : null; // old int? first = customers?[0].Orders?.Count(); // Chained PropertyChanged?.Invoke(this, args); // Invoke on ? 

String interpolation var s = String.Format("{0} is {1} year{{s}} old", p.Name, p.Age); var s = $"{p.Name} is {p.Age} year{{s}} old"; var s = $"{p.Name,20} is {p.Age:D3} year{{s}} old"; var s = $"{p.Name} is {p.Age} year{(p.Age == 1 ? "" : "s")} old"; 

nameof expressions if (x == null) throw new ArgumentNullException(nameof(x)); WriteLine(nameof(person.Address.ZipCode)); // prints "ZipCode" 

Index initializers var numbers = new Dictionary { [7] = "seven", [9] = "nine", [13] = "thirteen" }; 

Exception filters try { … } catch (MyException e) when (myfilter(e)) { … } private static bool Log(Exception e) { /* log it */ ; return false; } … try { … } catch (Exception e) when (Log(e)) {} 

Await in catch and finally blocks Resource res = null; try { res = await Resource.OpenAsync(…); // You could do this. } catch(ResourceException e) { await Resource.LogAsync(res, e); // Now you can do this … } finally { if (res != null) await res.CloseAsync(); // … and this. } 

MvvmCross & C#6 Building Native Cross-Platform Apps 

Why Mvvm? View Binder ViewModel Model Button Text 1. Action 1. Action 3. Command 5. Notify change 6. Change data 4. Access data 2. Event handling 

Why MvvmCross? ■ Cross-platform awesomeness! ■ Support for all major platforms ■ Most advanced Mvvm library for Xamarin and .NET cross platform ■ Large and engaged community ■ Fast release cycle ■ Clean and easy conventions Miguel de Icaza (Xamarin CTO) “I love MvvmCross” ■ Used by many enterprise companies e.g: - Microsoft - Xamarin inc. - Dutch government - Olo - Nokia Scott Hanselman (Microsoft Developer Evangelist) “I am really impressed with MvvmCross” 

MvvmCross supported platforms ■ Android ■ iOS ■ Windows ■ Xamarin.Forms ■ tvOS ■ Google wear ■ iWatch ■ Mac 

MvvmCross details Highlights ■ Flexible architecture ■ PCL based ■ Inversion of Control ■ Dependency injection ■ Value Converters ■ Bindings ■ Testable ■ Plugins Resources ■ Github.com/MvvmCross ■ MvvmCross.com ■ Slack (#mvvmcross) ■ Stackoverflow ■ Xamarin Forums 

Presenters Specifications ■ Customize view presentation ■ Platform-specific ■ Still retain View Model logic ■ Presentation hints Examples ■ Tabs / Panorama ■ Split View / Master-Detail ■ Fragments ■ Modals ■ Hamburger menu 

Plugins ■ Messenger ■ Phone Call ■ Picture Chooser ■ SQLite ■ Visibility ■ Web Browser + Many More! MvvmCross ■ Accelerometer ■ Download Cache ■ Email ■ File ■ Json ■ Localization ■ Location Plugins available at https://github.com/MvvmCross/MvvmCross-Plugins 

Generics ■ MvvmCross uses CoC (Convention over Configuration) by default - LoginView > LoginViewModel ■ Generics can be used too - LoginView : MvxActivity - MainView : MvxActivity ■ Possible to override in setup.cs - protected override IDictionary GetViewModelViewLookup() 

IoC (Inversion of Control) 1. Use interfaces 2. Define implementation of interfaces at runtime 3. Job done! :) ■ Singleton: Mvx.RegisterSingleton(); ■ Lazy: Mvx.ConstructAndRegisterSingleton(); ■ Dynamic: Mvx.RegisterType(); Mvx.Resolve(); 

Tips ■ Keep it simple ■ Separation of Concerns ■ Don’t try to invent the wheel again, use plugins, samples, etc ■ Use Xamarin player or GenyMotion as emulator for Android ■ Test all changes (UITest, Unit test, etc) ■ Use a common PCL profile (profile7 or profile259) or .NET Platform Standard ■ Enable “Analysis” XS > Preferences > Text Editor > Source Analysis > Enable ■ Get help on Slack: https://xamarinchat.herokuapp.com/ ■ Follow influencers on Twitter #Xamarin #MvvmCross ■ Join the MvvmCross LinkedIn group