Adds bindings for android.arch.lifecycle:extensions:1.0.0

[cosminstirbu]

Support Libraries Version (eg: 23.3.0):

26.1.0

Does this change any of the generated binding API's?

It only adds a new binding project for android.arch.lifecycle:extensions:1.0.0

Describe your contribution

As mentioned in #76 - being able to reference the new ViewModelProvider from Architecture Components (which can be found in android.arch.lifecycle:extensions) allows proper handling of the .NET ViewModel's lifecycle in relation to the Activity / Fragment's lifecycle (such as having the ViewModel survive during configuration changes such as screen rotation).

This is an usage example (that leverages MvvmLight):

using System; using Android.Arch.Lifecycle; using GalaSoft.MvvmLight; namespace TestArchitectureComponents.Extensions { public static class ViewModelProvierExtensions { public static T Get<T>(this ViewModelProvider viewModelProvier, Func<T> viewModelFactory) where T : ViewModelBase { var androidViewModelHolder = (AndroidViewModelHolder) viewModelProvier.Get(Java.Lang.Class.FromType(typeof(AndroidViewModelHolder))); return androidViewModelHolder.GetViewModel(viewModelFactory); } } /// Cannot make the class generic due to: Pending exception android.runtime.JavaProxyThrowable: System.NotSupportedException: Constructing instances of generic types from Java is not supported, as the type parameters cannot be determined. class AndroidViewModelHolder : Android.Arch.Lifecycle.ViewModel { private object _viewModel; public T GetViewModel<T>(Func<T> viewModelFactory) where T : ViewModelBase { if (_viewModel == null) { _viewModel = viewModelFactory(); } return _viewModel as T; } } } 

Your MvvmLight ViewModel:

 using System; using GalaSoft.MvvmLight; namespace TestArchitectureComponents.ViewModel { public class MainViewModel : ViewModelBase { public int Random { get; set; } = new Random().Next(); /// <summary> /// Initializes a new instance of the MainViewModel class. /// </summary> public MainViewModel() { } } } 

And your activity:

using System; using Android.App; using Android.OS; using Android.Arch.Lifecycle; using Android.Support.V4.App; using TestArchitectureComponents.Extensions; using TestArchitectureComponents.ViewModel; namespace TestArchitectureComponents { [Activity(Label = "TestArchitectureComponents", MainLauncher = true)] public class MainActivity : FragmentActivity { public int Random { get; set; } = new Random().Next(); protected override void OnCreate(Bundle savedInstanceState) { base.OnCreate(savedInstanceState); var viewModel = ViewModelProviders.Of(this).Get(() => ViewModelLocator.Current.Main); System.Diagnostics.Debug.WriteLine($"Activity random is {Random}, View Model random is: {viewModel.Random}"); // Set our view from the "main" layout resource SetContentView(Resource.Layout.Main); } } } 

When you'll rotate your screen you'll notice that

System.Diagnostics.Debug.WriteLine($"Activity random is {Random}, View Model random is: {viewModel.Random}"); prints a different number for the Activity - as it gets recreated, but it prints the same number for MainViewModel since it's kept alive during configuration changes.

Please review this thoroughly as I'm coming from an iOS / Android native background development so there are changes that I might have missed some things.

[cosminstirbu]

I've bumped android.arch.lifecycle:runtime to 1.0.3

I've also updated all the template.nuspec files that were referencing the previous version.

[cosminstirbu]

For now I didn't do any transformation to the generated bindings.

If there's something in particular you want me to look at - please let me know.

If you want me to clean up the template comments, I can do that.

[cosminstirbu]

Not sure if all these projects need to be referenced, or if referencing just the Fragment one should suffice since Fragment also references the projects above.