Setup.cs

public class Setup : MvxFormsAndroidSetup
{
    public Setup(Context applicationContext) : base(applicationContext)
    {
    }

    protected override void InitializeFirstChance()
    {
        base.InitializeFirstChance();
        Mvx.RegisterSingleton<IFileService>(new FileService());
    }

    protected override IMvxApplication CreateApp()
    {
        return new Core.CoreApp();
    }

    protected override MvvmCross.Forms.Core.MvxFormsApplication CreateFormsApplication()
    {
        return new Core.App();
    }

    protected override IMvxTrace CreateDebugTrace()
    {
        return new DebugTrace();
    }

    protected override IMvxIocOptions CreateIocOptions()
    {
        return new MvxIocOptions()
        {
            PropertyInjectorOptions = MvxPropertyInjectorOptions.All
        };
    }
}