Xamarin.Tip – Xamarin.Forms Long Press Effect

Here’s a quick and helpful tool to use in your Xamarin.Forms applications! How many times have you wanted to add a long press handler? Seems like something that should be a simple Gesture built into the platform, but we have to fend for ourselves. Luckily the solution is pretty simple using Xamarin.Forms Effects!

Let’s first create our shared Effect in our shared code:

LongPressedEffect.cs

    /// <summary>
    /// Long pressed effect. Used for invoking commands on long press detection cross platform
    /// </summary>
    public class LongPressedEffect : RoutingEffect
    {
        public LongPressedEffect() : base("MyApp.LongPressedEffect")
        {
        }

        public static readonly BindableProperty CommandProperty = BindableProperty.CreateAttached("Command", typeof(ICommand), typeof(LongPressedEffect), (object)null);
        public static ICommand GetCommand(BindableObject view)
        {
            return (ICommand)view.GetValue(CommandProperty);
        }

        public static void SetCommand(BindableObject view, ICommand value)
        {
            view.SetValue(CommandProperty, value);
        }


        public static readonly BindableProperty CommandParameterProperty = BindableProperty.CreateAttached("CommandParameter", typeof(object), typeof(LongPressedEffect), (object)null);
        public static object GetCommandParameter(BindableObject view)
        {
            return view.GetValue(CommandParameterProperty);
        }

        public static void SetCommandParameter(BindableObject view, object value)
        {
            view.SetValue(CommandParameterProperty, value);
        }
    }

Now we have 2 bindable properties – the Command that we want to bind when the long press is detected and the CommandParameter to pass into the Command.

We can use these in our native Effect implementations to invoke when the press is detected. Let’s create our Android implementation.

AndroidLongPressedEffect.cs

[assembly: ResolutionGroupName("MyApp")]
[assembly: ExportEffect(typeof(AndroidLongPressedEffect), "LongPressedEffect")]
namespace AndroidAppNamespace.Effects
{
    /// <summary>
    /// Android long pressed effect.
    /// </summary>
    public class AndroidLongPressedEffect : PlatformEffect
    {
        private bool _attached;

        /// <summary>
        /// Initializer to avoid linking out
        /// </summary>
        public static void Initialize() { }

        /// <summary>
        /// Initializes a new instance of the
        /// <see cref="T:Yukon.Application.AndroidComponents.Effects.AndroidLongPressedEffect"/> class.
        /// Empty constructor required for the odd Xamarin.Forms reflection constructor search
        /// </summary>
        public AndroidLongPressedEffect()
        {
        }

        /// <summary>
        /// Apply the handler
        /// </summary>
        protected override void OnAttached()
        {
            //because an effect can be detached immediately after attached (happens in listview), only attach the handler one time.
            if (!_attached)
            {
                if (Control != null)
                {
                    Control.LongClickable = true;
                    Control.LongClick += Control_LongClick;
                }
                else
                {
                    Container.LongClickable = true;
                    Container.LongClick += Control_LongClick;
                }
                _attached = true;
            }
        }

        /// <summary>
        /// Invoke the command if there is one
        /// </summary>
        /// <param name="sender">Sender.</param>
        /// <param name="e">E.</param>
        private void Control_LongClick(object sender, Android.Views.View.LongClickEventArgs e)
        {
            Console.WriteLine("Invoking long click command");
            var command = LongPressedEffect.GetCommand(Element);
            command?.Execute(LongPressedEffect.GetCommandParameter(Element));
        }

        /// <summary>
        /// Clean the event handler on detach
        /// </summary>
        protected override void OnDetached()
        {
            if (_attached)
            {
                if (Control != null)
                {
                    Control.LongClickable = true;
                    Control.LongClick -= Control_LongClick;
                }
                else
                {
                    Container.LongClickable = true;
                    Container.LongClick -= Control_LongClick;
                }
                _attached = false;
            }
        }
    }

And now for iOS:

iOSLongPressedEffect.cs

[assembly: ResolutionGroupName("MyApp")]
[assembly: ExportEffect(typeof(iOSLongPressedEffect), "LongPressedEffect")]
namespace iOSNamespace.Effects
{
    /// <summary>
    /// iOS long pressed effect
    /// </summary>
    public class iOSLongPressedEffect : PlatformEffect
    {
        private bool _attached;
        private readonly UILongPressGestureRecognizer _longPressRecognizer;
        /// <summary>
        /// Initializes a new instance of the
        /// <see cref="T:Yukon.Application.iOSComponents.Effects.iOSLongPressedEffect"/> class.
        /// </summary>
        public iOSLongPressedEffect()
        {
            _longPressRecognizer = new UILongPressGestureRecognizer(HandleLongClick);
        }

        /// <summary>
        /// Apply the handler
        /// </summary>
        protected override void OnAttached()
        {
            //because an effect can be detached immediately after attached (happens in listview), only attach the handler one time
            if (!_attached)
            {
                Container.AddGestureRecognizer(_longPressRecognizer);
                _attached = true;
            }
        }

        /// <summary>
        /// Invoke the command if there is one
        /// </summary>
        private void HandleLongClick()
        {
            var command = LongPressedEffect.GetCommand(Element);
            command?.Execute(LongPressedEffect.GetCommandParameter(Element));
        }

        /// <summary>
        /// Clean the event handler on detach
        /// </summary>
        protected override void OnDetached()
        {
            if (_attached)
            {
                Container.RemoveGestureRecognizer(_longPressRecognizer);
                _attached = false;
            }
        }

    }

Now that we have our 2 implementations, let’s use it in our XAML!

MyPage.xaml

<Label Text="Long Press Me!" effects:LongPressedEffect.Command="{Binding ShowAlertCommand}" effects:LongPressedEffect.CommandParameter="{Binding .}">
    <Label.Effects>
        <effects:LongPressedEffect />
    </Label.Effects>
</Label>

Now you can start handling long presses on any control! If you want to add it to a ListView just attach it to either the ViewCell or the internal View of the cell.

 

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

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Xamarin.NuGet – Xamarin.Forms Dynamic Bindable StackLayout

I recently released a component I commonly use in my Xamarin.Forms applications for binding data to a wrapping layout here: Xamarin.NuGet – DynamicWrapLayout Announcement! In the spirit of this type of control, I’ve also released a new NuGet package for a bindable DynamicStackLayout. It’s a simple control that allows you to create a StackLayout and bind an ItemsSource collection and an ItemTemplate. This is useful for smaller, but dynamic collections with the use of the orientation changing of a StackLayout. This means you could have a horizontally scrolling list of cards, bind the orientation or change it to vertical, and play with positioning more easily than using a ListView. I would still highly suggest using a ListView over this control for a standard vertical stack of dynamic content since this control does NOT use any view recycling or virtualization which can cause performance issues with large collections or constantly changing collection.

Get it here

NuGet: https://www.nuget.org/packages/DynamicStackLayout

Github: https://github.com/SuavePirate/DynamicStackLayout

In the end, you get something like this!

Be sure to read the documentation below:

DynamicStackLayout

A Xamarin.Forms layout for creating dynamically wrapped views. Inspired by the WrapLayout example: https://developer.xamarin.com/samples/xamarin-forms/UserInterface/CustomLayout/WrapLayout/

Installation

It’s on NuGet! https://www.nuget.org/packages/DynamicStackLayout/

Install-Package DynamicStackLayout

Be sure to install in all projects that use it.

Usage

There are two key properties that make this control useful – the ItemsSource (like a ListView) and the ItemTemplate (although, you can also just add children to the view – it does both!)
Be sure to wrap it in a ScrollView though

XAML

Add the xmlns:

xmlns:suave=&quot;clr-namespace:SuaveControls.DynamicStackLayout;assembly=SuaveControls.DynamicStackLayout&quot;

Use it in your View:

&lt;ScrollView&gt;
    &lt;suave:DynamicStackLayout ItemsSource=&quot;{Binding Items}&quot; HorizontalOptions=&quot;Fill&quot;&gt;
        &lt;suave:DynamicStackLayout.ItemTemplate&gt;
            &lt;DataTemplate&gt;
                &lt;StackLayout BackgroundColor=&quot;Gray&quot; WidthRequest=&quot;120&quot; HeightRequest=&quot;180&quot;&gt;
                    &lt;Label Text=&quot;{Binding .}&quot; VerticalOptions=&quot;FillAndExpand&quot; HorizontalOptions=&quot;FillAndExpand&quot; VerticalTextAlignment=&quot;Center&quot; HorizontalTextAlignment=&quot;Center&quot; /&gt;
                &lt;/StackLayout&gt;
            &lt;/DataTemplate&gt;
        &lt;/suave:DynamicStackLayout.ItemTemplate&gt;
    &lt;/suave:DynamicStackLayout&gt;
&lt;/ScrollView&gt;

Don’t like data-binding and want to just use child views? You can do that too!

&lt;ScrollView&gt;
    &lt;suave:DynamicStackLayout HorizontalOptions=&quot;Fill&quot;&gt;
      &lt;StackLayout BackgroundColor=&quot;Gray&quot; WidthRequest=&quot;120&quot; HeightRequest=&quot;180&quot;&gt;
          &lt;Label Text=&quot;0&quot; TextColor=&quot;White&quot; VerticalOptions=&quot;FillAndExpand&quot; HorizontalOptions=&quot;FillAndExpand&quot; VerticalTextAlignment=&quot;Center&quot; HorizontalTextAlignment=&quot;Center&quot; /&gt;
      &lt;/StackLayout&gt;
      &lt;StackLayout BackgroundColor=&quot;Gray&quot; WidthRequest=&quot;120&quot; HeightRequest=&quot;180&quot;&gt;
          &lt;Label Text=&quot;1&quot; TextColor=&quot;White&quot; VerticalOptions=&quot;FillAndExpand&quot; HorizontalOptions=&quot;FillAndExpand&quot; VerticalTextAlignment=&quot;Center&quot; HorizontalTextAlignment=&quot;Center&quot; /&gt;
      &lt;/StackLayout&gt;
      &lt;StackLayout BackgroundColor=&quot;Gray&quot; WidthRequest=&quot;120&quot; HeightRequest=&quot;180&quot;&gt;
          &lt;Label Text=&quot;2&quot; TextColor=&quot;White&quot; VerticalOptions=&quot;FillAndExpand&quot; HorizontalOptions=&quot;FillAndExpand&quot; VerticalTextAlignment=&quot;Center&quot; HorizontalTextAlignment=&quot;Center&quot; /&gt;
      &lt;/StackLayout&gt;
      &lt;StackLayout BackgroundColor=&quot;Gray&quot; WidthRequest=&quot;120&quot; HeightRequest=&quot;180&quot;&gt;
          &lt;Label Text=&quot;3&quot; TextColor=&quot;White&quot; VerticalOptions=&quot;FillAndExpand&quot; HorizontalOptions=&quot;FillAndExpand&quot; VerticalTextAlignment=&quot;Center&quot; HorizontalTextAlignment=&quot;Center&quot; /&gt;
      &lt;/StackLayout&gt;
      &lt;StackLayout BackgroundColor=&quot;Gray&quot; WidthRequest=&quot;120&quot; HeightRequest=&quot;180&quot;&gt;
          &lt;Label Text=&quot;4&quot; TextColor=&quot;White&quot; VerticalOptions=&quot;FillAndExpand&quot; HorizontalOptions=&quot;FillAndExpand&quot; VerticalTextAlignment=&quot;Center&quot; HorizontalTextAlignment=&quot;Center&quot; /&gt;
      &lt;/StackLayout&gt;
    &lt;/suave:DynamicStackLayout&gt;
&lt;/ScrollView&gt;

Features

  • Bindable child views
  • Bindable to collections
  • Handles layout changing well (try rotating the device)
  • Doesn’t require custom renderers (All Xamarin.Forms baby!)

Notes

This does not use any native view virtualization, which means performance does not scale well with extremely large data sets.

Coming soon

  • ItemSelected event and SelectedItem bindable property (for now, you can add custom gestures and commands to your DataTemplate and handle the events yourself)
  • Better Collection Updating

 

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.NuGet – DynamicWrapLayout Announcement!

It’s been a little while since I’ve posted about any new Xamarin Controls or updates, but here’s a great one!

I needed to create a layout that could bind to a collection of data in Xamarin.Forms that fit to a dynamic grid that also scaled to larger devices and orientation changes. I thought about creating a new custom renderer that uses the RecyclerView with a GridLayoutManager and a UICollectionView with a custom layout. However, I didn’t need to bind to tons of data, so I decided to create a new control that is entirely Xamarin.Forms – No custom renderers!

I’ve called it the DynamicWrapLayout since it was inspired by the WrapLayout from Charles Petzold and David Britch.

Get it on NuGet: https://www.nuget.org/packages/DynamicWrapLayout/
Get the source on GitHub: https://github.com/SuavePirate/DynamicWrapLayout

Because it is all Xamarin.Forms, it should work on all the platforms that Forms supports! So use it everywhere! I’ll create another post about how I built it if you want to work on your own implementation, but for now, you can read the documentation on the control below.

Documentation

DynamicWrapLayout

A Xamarin.Forms layout for creating dynamically wrapped views. Inspired by the WrapLayout example: https://developer.xamarin.com/samples/xamarin-forms/UserInterface/CustomLayout/WrapLayout/

Installation

It’s on NuGet! https://www.nuget.org/packages/DynamicWrapLayout/

Install-Package DynamicWrapLayout

Be sure to install in all projects that use it.

Usage

There are two key properties that make this control useful – the ItemsSource (like a ListView) and the DataTemplate (although, you can also just add children to the view – it does both!)
Be sure to wrap it in a ScrollView though

XAML

Add the xmlns:

xmlns:suave="clr-namespace:SuaveControls.DynamicWrapLayout;assembly=SuaveControls.DynamicWrapLayout"

Use it in your View:

<ScrollView>
    <suave:DynamicWrapLayout ItemsSource="{Binding Items}" HorizontalOptions="Fill">
        <suave:DynamicWrapLayout.ItemTemplate>
            <DataTemplate>
                <StackLayout BackgroundColor="Gray" WidthRequest="120" HeightRequest="180">
                    <Label Text="{Binding .}" TextColor="White" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" />
                </StackLayout>
            </DataTemplate>
        </suave:DynamicWrapLayout.ItemTemplate>
    </suave:DynamicWrapLayout>
</ScrollView>

Don’t like data-binding and want to just use child views? You can do that too!

<ScrollView>
    <suave:DynamicWrapLayout HorizontalOptions="Fill">
      <StackLayout BackgroundColor="Gray" WidthRequest="120" HeightRequest="180">
          <Label Text="0" TextColor="White" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" />
      </StackLayout>
      <StackLayout BackgroundColor="Gray" WidthRequest="120" HeightRequest="180">
          <Label Text="1" TextColor="White" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" />
      </StackLayout>
      <StackLayout BackgroundColor="Gray" WidthRequest="120" HeightRequest="180">
          <Label Text="2" TextColor="White" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" />
      </StackLayout>
      <StackLayout BackgroundColor="Gray" WidthRequest="120" HeightRequest="180">
          <Label Text="3" TextColor="White" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" />
      </StackLayout>
      <StackLayout BackgroundColor="Gray" WidthRequest="120" HeightRequest="180">
          <Label Text="4" TextColor="White" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" />
      </StackLayout>
    </suave:DynamicWrapLayout>
</ScrollView>

Features

  • Bindable child views
  • Bindable to collections
  • Handles layout changing well (try rotating the device)
  • Doesn’t require custom renderers (All Xamarin.Forms baby!)

What does this thing look like?

Android:


iOS:


Notes

This does not use any native view virtualization, which means performance does not scale well with extremely large data sets.

Coming soon

  • ItemSelected event and SelectedItem bindable property (for now, you can add custom gestures and commands to your DataTemplate and handle the events yourself)
     

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.Forms Floating Action Button NuGet Announcement

As promised, here is another release of one of my GitHub libraries for Xamarin! This time we are talking about the FloatingActionButton or “FAB”!

Here are some important links:

GitHub project: https://github.com/SuavePirate/Xamarin.Forms.Controls.FloatingActionButton
NuGet package: https://www.nuget.org/packages/SuaveControls.FloatingActionButton

Don’t forget to read up on my original post on how to create your own FloatingActionButton and how to use it: Xamarin.Controls – Xamarin.Forms FloatingActionButton (including iOS!)

Documentation


Xamarin.Forms.Controls.FloatingActionButton

A custom view to create a FloatingActionButton for both Android and iOS as part of Material Design

That’s right, even on iOS!

How to use

Clone the repository and open include the src projects in your Xamarin.Forms and Platform projects.

Now Available on NuGet!

Install-Package SuaveControls.FloatingActionButton

Special note for iOS: Make sure to call FloatingActionButtonRenderer.InitRenderer(); in your AppDelegate.cs in order to avoid linking it out.

Then you can include it in your XAML or call it from C# (See the example projects for a demo):

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:SuaveControls.FabExample"
             xmlns:controls="clr-namespace:SuaveControls.Views;assembly=SuaveControls.FloatingActionButton"
             x:Class="SuaveControls.FabExample.MainPage">
    <StackLayout Margin="32">
        <Label Text="This is a Floating Action Button!" 
           VerticalOptions="Center" 
           HorizontalOptions="Center"/>

        <controls:FloatingActionButton x:Name="FAB" HorizontalOptions="CenterAndExpand" WidthRequest="50" HeightRequest="50"  VerticalOptions="CenterAndExpand" Image="ic_add_white.png" ButtonColor="#03A9F4" Clicked="Button_Clicked"/>
    </StackLayout>
</ContentPage>

Android Example

Android Floating Action Button

iOS Example

iOS Floating Action Button

TODO:

  • Make it more flexible. Add Different color states, add sizing adjustments, etc.
  • Create UWP implementation
  • Create Xamarin Component

Come support the project and join the contributors list! We would love to see this TODO list dropped to nothing!

 

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.Forms BadgeView NuGet Announcement!

As promised, here is another release of one of my GitHub libraries for Xamarin! This time we are talking about the BadgeView​!

Here are some important links:

GitHub project: https://github.com/SuavePirate/BadgeView
NuGet package: https://www.nuget.org/packages/BadgeView

Don’t forget to read up on my original post on how to create your own BadgeView and how to use it: Xamarin.Controls – BadgeView

Documentation

 


BadgeView

A simple Xamarin.Forms control to display a round badge

Now available on nuget! https://www.nuget.org/packages/BadgeView

Installation

Install-Package BadgeView

Usage

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:badge="clr-namespace:BadgeView.Shared;assembly=BadgeView.Shared" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="BadgeViewExample.BadgePage">
    <ContentPage.Content>
        <StackLayout Orientation="Horizontal" HorizontalOptions="CenterAndExpand" VerticalOptions="Center">
            <Label HorizontalTextAlignment="Center" Text="Look at me!" />
            <badge:BadgeView Text="3" BadgeColor="Green" VerticalOptions="Center" HorizontalOptions="End" />
        </StackLayout>
    </ContentPage.Content>
</ContentPage>

With Bindings

<badge:BadgeView Text="{Binding BadgeNumber}" BadgeColor="{Binding BadgeColor}" VerticalOptions="Center" HorizontalOptions="End" />

Without XAML

var badge = new BadgeView()
{
    Text = "4",
    BadgeColor = Color.Red
};

Additional Resources

Check out my blog post on how to build your own if you want!
https://alexdunn.org/2017/03/15/xamarin-controls-badgeview/

 

// TODO:

I’m still working on adding UWP support, but if you want to help contribute to the repository, please do!

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

.NET Flux Toolkit Nuget Announcement

Last week I mentioned that I was going to be publishing some of my GitHub library projects on Nuget to make them easier to integrate into your projects – Here’s the newest library for using the Flux in your .NET applications such as Xamarin, UWP, WPF, WinForms, and even ASP.NET.

Nuget: https://www.nuget.org/packages/FluxToolkit/
GitHub: https://github.com/SuavePirate/FluxToolkit/

Here’s how to get started!

FluxToolkit

A super simple library to enable the implementation of Flux in .NET Applications such as Xamarin, UWP, WPF, and more. It contains some base level Flux components to help you get started with your implementation faster.

What is Flux?

Flux is a design pattern created by Facebook with the purpose of creating robust data-driven UI components and handles the flow of data between components and outward to services.

Components

Flux consists of 4 major components – Stores, Actions, Components, and the Dispatcher

Stores

Stores are responsible for containing and managing data for a single domain or data type. Stores listen to the dispatcher for certain events and use the data from the dispatcher to update their data, handle errors, and then pass that update down to the components that are subscribed to the store.

Actions

Actions are responsible for piping events through the dispatcher. Actions are invoked from Components or from background processes. They can also handle some small business logic such as data mapping or talking to external services.

Components

Components are the UI and UI logic layers. They are responsible for displaying views to the users and for handling user events. They invoke Actions and subsribe to Stores to handle updates to the data.

Dispatcher

A single dispatcher is responsible for the Pub/Sub mechanism of events invoked from Actions. Stores subscribe to events by name through the Dispatcher.

How does it work with MVVM and data binding?

ViewModels can be considered part of the Component layer but are separated from the actual UI/Views. This means that the ViewModels are responsible for invoking Actions, and subscribing to Stores. The Views themselves are only responsible for showing the UI and communicating to the ViewModel.

Getting Started

Install

The FluxToolkit is available on Nuget: https://www.nuget.org/packages/FluxToolkit It has no external dependencies and should work with any .NET Standard library or project including Xamarin, Xamarin.Forms, UWP, WPF, and even WinForms. It has not been used for web application development, but it is compatible with ASP.NET projects.

Install the nuget package with the nuget package manager or via the Package Manager command line:

Install-Package FluxToolkit

Create your Stores

Use the StoreBase class from the FluxToolkit to implement your unique stores for your different data types. It contains a generic Data field based on the TData type you pass into the definition. Now you don’t have to worry about communicating to the dispatcher for pub/sub – simply call the base methods for Subsribe and Unsubscribe.

Ensure that you are not using multiple instances of your Stores, but rather should be using either a Singleton or Inversion of Control with Dependency Injection to pass the implementation of your Store to the Components that require it through the constructor. Constantly creating new Stores can cause memory leaks due to the event subscriptions.

Here’s an example store implementation:

    /// <summary>
    /// Event store for holding and managing todo items
    /// </summary>
    public class TodoStore : StoreBase<ObservableCollection<Todo>>
    {
        /// <summary>
        /// Creates a new store and handles subscriptions to the dispatcher
        /// </summary>
        public TodoStore()
        {
            Subscribe<string>(TodoActionTypes.ADD_TODO);
            Subscribe(TodoActionTypes.DELETE_COMPLETED_TODOS);
            Subscribe<string>(TodoActionTypes.DELETE_TODO);
            Subscribe<Todo>(TodoActionTypes.EDIT_TODO);
            Subscribe(TodoActionTypes.TOGGLE_ALL_TODOS);
            Subscribe<string>(TodoActionTypes.TOGGLE_TODO);

            Data = new ObservableCollection<Todo>();
        }

        /// <summary>
        /// Processes an event from the dispatcher before emitting it.
        /// </summary>
        /// <typeparam name="TData"></typeparam>
        /// <param name="eventType"></param>
        /// <param name="data"></param>
        protected override void ReceiveEvent<TData>(string eventType, TData data)
        {
            try
            {
                Error = null;
                switch (eventType)
                {
                    case TodoActionTypes.ADD_TODO:
                        Data.Add(new Todo
                        {
                            Id = Guid.NewGuid().ToString(),
                            Text = data as string,
                            IsComplete = false
                        });
                        break;
                    case TodoActionTypes.DELETE_COMPLETED_TODOS:
                        var itemsToRemove = Data.Where(t => t.IsComplete);
                        foreach(var item in itemsToRemove.ToList())
                        {
                            Data.Remove(item);
                        }
                        break;
                    case TodoActionTypes.DELETE_TODO:
                        var itemToRemove = Data.FirstOrDefault(t => t.Id == data as string);
                        if (itemToRemove != null)
                            Data.Remove(itemToRemove);
                        break;
                    case TodoActionTypes.EDIT_TODO:
                        var itemToEdit = Data.FirstOrDefault(t => t.Id == (data as Todo).Id);
                        if (itemToEdit != null)
                            itemToEdit.Text = (data as Todo).Text;
                        break;
                    case TodoActionTypes.TOGGLE_ALL_TODOS:
                        var areAllComplete = !Data.Any(t => !t.IsComplete);
                        foreach(var todo in Data)
                        {
                            todo.IsComplete = !areAllComplete;
                        }
                        break;
                    case TodoActionTypes.TOGGLE_TODO:
                        var itemToToggle = Data.First(t => t.Id == (data as string));
                        if (itemToToggle != null)
                            itemToToggle.IsComplete = !itemToToggle.IsComplete;
                        break;

                }
            }
            catch (Exception ex)
            {
                // if something goes wrong, set the error before emitting
                Error = ex.Message;
            }
           
            base.ReceiveEvent(eventType, data);
        }
    }

Create your Actions

Create an Actions class for each of your main data types. These actions will call to the Dispatcher to fire events and will also need to implement IActions in order to properly handle the pub/sub mechanism.

    /// <summary>
    /// Actions to be taken against Todo items
    /// </summary>
    public class TodoActions : IActions
    {
        public void AddTodo(string text)
        {
            Dispatcher.Send<IActions, string>(this, TodoActionTypes.ADD_TODO, text);
        }

        public void DeleteCompletedTodos()
        {
            Dispatcher.Send<IActions>(this, TodoActionTypes.DELETE_COMPLETED_TODOS);
        }

        public void DeleteTodo(string id)
        {
            Dispatcher.Send<IActions, string>(this, TodoActionTypes.DELETE_TODO, id);
        }

        public void EditTodo(string id, string text)
        {
            Dispatcher.Send<IActions, Todo>(this, TodoActionTypes.EDIT_TODO, new Todo
            {
                Id = id,
                Text = text
            });
        }

        public void StartEditingTodo(string id)
        {
            Dispatcher.Send<IActions, string>(this, TodoActionTypes.START_EDITING_TODO, id);
        }

        public void StopEditingTodo()
        {
            Dispatcher.Send<IActions>(this, TodoActionTypes.STOP_EDITING_TODO);
        }

        public void ToggleAllTodos()
        {
            Dispatcher.Send<IActions>(this, TodoActionTypes.TOGGLE_ALL_TODOS);
        }

        public void ToggleTodo(string id)
        {
            Dispatcher.Send<IActions, string>(this, TodoActionTypes.TOGGLE_TODO, id);
        }
        
    }

Define your ActionTypes

For each of your data types, you’ll need to define some ActionTypes which translate to the id or name of the events your Actions are invoking through the Dispatcher.

    /// <summary>
    /// Different types of actions that can be completed within the context of Todo items
    /// </summary>
    public class TodoActionTypes
    {
        public const string ADD_TODO = "add_todo";
        public const string DELETE_COMPLETED_TODOS = "delete_completed_todos";
        public const string DELETE_TODO = "delete_todo";
        public const string EDIT_TODO = "edit_todo";
        public const string START_EDITING_TODO = "start_editing_todo";
        public const string STOP_EDITING_TODO = "stop_editing_todo";
        public const string TOGGLE_ALL_TODOS = "toggle_all_todos";
        public const string TOGGLE_TODO = "toggle_todo";
        public const string UPDATE_DRAFT = "update_draft";
    }

Wire up your Components (with MVVM or without)

Have your components subscribe to the Stores that are appropriate for the data need, and invoke the Actions they need. This is a great place to place inject your Stores and Actions into the constructor of your Componentswhether it is through a ViewModel or an ActivityViewController, or Xamarin.Forms.Page.

    public class TodoListPageViewModel : BasePageViewModel
    {
        private readonly TodoStore _todoStore;
        private readonly TodoActions _todoActions;
        private ObservableCollection<Todo> _items;
        private ICommand _createCommand;
        private ICommand _toggleCommand;
        private ICommand _toggleAllCommand;
        private ICommand _deleteCommand;
        private ICommand _deleteCompletedCommand;
        private ICommand _editCommand;
        private ICommand _populateCommand;

        public ICommand CreateCommand
        {
            get
            {
                return _createCommand ??
                    (_createCommand = new RelayCommand(async () =>
                    {
                        var result = await UserDialogs.Instance.PromptAsync(string.Empty, "New", "Done", "Cancel", "Todo...");
                        if (result.Ok)
                        {
                            _todoActions.AddTodo(result.Text);
                        }
                    }));
            }
        }

        public ICommand EditCommand
        {
            get
            {
                return _editCommand ??
                    (_editCommand = new RelayCommand<Todo>(async (t) =>
                    {
                        var result = await UserDialogs.Instance.PromptAsync(new PromptConfig()
                            .SetText(t.Text)
                            .SetTitle("Edit")
                            .SetOkText("Done")
                            .SetCancelText("Cancel")
                            .SetPlaceholder("Todo..."));
                        if (result.Ok)
                        {
                            _todoActions.EditTodo(t.Id, result.Text);
                        }
                    }));
            }
        }

        public ICommand ToggleCommand
        {
            get
            {
                return _toggleCommand ??
                    (_toggleCommand = new RelayCommand<Todo>((t) =>
                    {
                        _todoActions.ToggleTodo(t.Id);
                    }));
            }
        }

        public ICommand ToggleAllCommand
        {
            get
            {
                return _toggleAllCommand ??
                    (_toggleAllCommand = new RelayCommand(() =>
                    {
                        _todoActions.ToggleAllTodos();
                    }));
            }
        }

        public ICommand DeleteCommand
        {
            get
            {
                return _deleteCommand ??
                    (_deleteCommand = new RelayCommand<Todo>((t) =>
                    {
                        _todoActions.DeleteTodo(t.Id);
                    }));
            }
        }

        public ICommand DeleteCompletedCommand
        {
            get
            {
                return _deleteCompletedCommand ??
                    (_deleteCompletedCommand = new RelayCommand(() =>
                    {
                        _todoActions.DeleteCompletedTodos();
                    }));
            }
        }

        public ICommand PopulateCommand
        {
            get
            {
                return _populateCommand ??
                    (_populateCommand = new RelayCommand(() =>
                    {
                        for(var i = 1; i < 20; i++)
                        {
                            _todoActions.AddTodo($"New Item {i}");
                            Task.Delay(200);
                        }
                    }));
            }
        }

        public ObservableCollection<Todo> Items
        {
            get
            {
                return _todoStore.Data;
            }
        }

        public TodoListPageViewModel(TodoStore todoStore, TodoActions todoActions)
        {
            _todoStore = todoStore;
            _todoActions = todoActions;
            _todoStore.OnEmitted += TodoStore_OnEmitted;
        }

        /// <summary>
        /// Processes events from the todo store and updates any UI that isn't handled automatically
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void TodoStore_OnEmitted(object sender, StoreEventArgs e)
        {
            switch (e.EventType)
            {
                case TodoActionTypes.ADD_TODO:
                    if(_todoStore.Error == null)
                    {
                        UserDialogs.Instance.Toast("Item added");
                    }
                    break;
                case TodoActionTypes.DELETE_COMPLETED_TODOS:
                    if (_todoStore.Error == null)
                    {
                        UserDialogs.Instance.Toast("Items deleted");
                    }
                    break;
                case TodoActionTypes.DELETE_TODO:
                    if (_todoStore.Error == null)
                    {
                        UserDialogs.Instance.Toast("Item deleted");
                    }
                    break;
                case TodoActionTypes.TOGGLE_ALL_TODOS:
                    if (_todoStore.Error == null)
                    {
                        UserDialogs.Instance.Toast("Items toggled");
                    }
                    break;
                case TodoActionTypes.TOGGLE_TODO:
                    if (_todoStore.Error == null)
                    {
                        UserDialogs.Instance.Toast("Item toggled");
                    }
                    break;
            }
            if(_todoStore.Error != null)
            {
                UserDialogs.Instance.ShowError(_todoStore.Error);
            }
        }
    }

Contributing

Want to add additional examples or more tooling to help people develop their apps with Flux? Fork this repository and create a pull request!

Additional Resources

 

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.Nuget – Coming to a Nuget Package Near You

Your voices have been heard – I’m bringing all my helpful controls and libraries to nuget!

Over the next two weeks, I will be going through each one of my projects and getting them nuget-ready. I’ll then be putting them up on nuget and announcing their individual releases here on my blog.

Here’s what you can expect to see on nuget:

So stay tuned, and if you want to contribute to any of these tools, please fork those repositories!

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.