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The Behaviors Toolkit for Xamarin

The Behaviors Toolkit for Xamarin is an easy-to-use means of adding common and reusable interactivity to your Xamarin applications with minimal code. Use of the Behaviors Toolkit for Xamarin is governed by the MIT License.

Build Status

Build status

Getting Started

As a primary Windows (XAML) developer, I've always enjoyed using the behaviors to easily add, with just some lines of code, some great features to any controls. Since I work with Xamarin, I've always thought it could be a good idea to get this functionality in the Xamarin projects.

So welcome to the home of the Behaviors Toolkit for Xamarin, a custom implementation of the XAML behaviors for the Xamarin (Android / iOS) projects!

Current Release

Current release (0.0.3) is available from Nuget: https://www.nuget.org/packages/Xamarin.Behaviors.Toolkit/

Code Example

Using a behavior

To attach a behavior to a control (Button, EditText, etc.), you just have to use the AttachBehavior method.

Take a look at the following code sample (for Xamarin.Android) showing how to use a behavior in an application, just with a snippet of code:

var mySecondEditText = FindViewById<EditText>(Resource.Id.MySecondEditText);
mySecondEditText.AttachBehavior(new SelectAllOnFocusBehavior());

Creating a behavior

The Behaviors Toolkit for Xamarin use the same architecture as the Microsoft behaviors which can be used in any XAML application. To create your own behavior, you just have to inherit from the Behavior<T> class and override the methods OnAttached and/or OnDetaching. To reference the control on which the behavior is attached, you can access the property AssociatedObject:

/// <summary>
/// Behavior used on an EditText object and used to hide the software keyboard when one of the following key is pressed: "Done", "Search" or "Go"
/// </summary>
public class HideKeyboardOnEnterKeyBehavior : Behavior<EditText>
{
    /// <summary>
    /// Gets or sets the application context.
    /// </summary>
    /// <value>
    /// The application context.
    /// </value>
    public Context ApplicationContext { get; set; }

    private EventHandler<TextView.EditorActionEventArgs> _editorActionEventHandler;

    /// <summary>
    /// Method to override when the behavior is attached to the view.
    /// </summary>
    /// <exception cref="System.InvalidOperationException">ApplicationContext property needs to be set in order to use this behavior.</exception>
    protected override void OnAttached()
    {
        if (this.ApplicationContext == null)
        {
            throw new InvalidOperationException("ApplicationContext property needs to be set in order to use this behavior.");
        }

        _editorActionEventHandler = (sender, args) =>
        {
            if (args.ActionId == ImeAction.Done || args.ActionId == ImeAction.Search || args.ActionId == ImeAction.Go || args.ActionId == ImeAction.Next)
            {
                var inputManager = (InputMethodManager)this.ApplicationContext.GetSystemService(Context.InputMethodService);
                inputManager.HideSoftInputFromWindow(this.AssociatedObject.WindowToken, HideSoftInputFlags.None);

                args.Handled = true;
            }
        };

        this.AssociatedObject.EditorAction += _editorActionEventHandler;
    }

    /// <summary>
    /// Method to override when the behavior is removed from the view.
    /// </summary>
    protected override void OnDetaching()
    {
        if (_editorActionEventHandler != null)
        {
            this.AssociatedObject.EditorAction -= _editorActionEventHandler;
        }
    }
}

Here is another sample behavior, for Xamarin.iOS applications:

/// <summary>
/// Behavior used on an EditText object and used to select all the text within it when it has focus
/// </summary>
public class SelectAllOnFocusBehavior : Behavior<UITextField>
{
    private EventHandler _editingDidBeginEventHandler;

    /// <summary>
    /// Method to override when the behavior is attached to the view.
    /// </summary>
    protected override void OnAttached()
    {
        _editingDidBeginEventHandler = (sender, e) =>
        {
            this.AssociatedObject.PerformSelector(new Selector("selectAll"), null, 0.0f);
        };

        this.AssociatedObject.EditingDidBegin += _editingDidBeginEventHandler;
    }

    /// <summary>
    /// Method to override when the behavior is removed from the associatedObject.
    /// </summary>
    protected override void OnDetaching()
    {
        if (_editingDidBeginEventHandler != null)
        {
            this.AssociatedObject.EditingDidBegin -= _editingDidBeginEventHandler;
        }
    }
}

Todo

  • Add more built-in behaviors for Xamarin.Android projects
  • Add more built-in behaviors for Xamarin.iOS projects

More Info