Getting Started with Xamarin CheckBox (SfCheckBox)

This section explains the steps required to configure the SfCheckBox control in a real-time scenario and provides a walk-through on some of the customization features available in SfCheckBox control.

Adding SfCheckBox reference

You can add SfCheckBox reference using one of the following methods:

Method 1: Adding SfCheckBox reference from nuget.org

Syncfusion Xamarin components are available in nuget.org. To add SfCheckBox to your project, open the NuGet package manager in Visual Studio, search for Syncfusion.Xamarin.Buttons, and then install it.

Xamarin.Forms CheckBox NuGet

NOTE

  • Install the same version of SfCheckBox NuGet in all the projects.
  • In addition, you need to install the Syncfusion.Xamarin.Buttons.WPF package for Xamarin.Forms WPF platform only.

Method 2: Adding SfCheckBox reference from toolbox

Syncfusion also provides Xamarin Toolbox. Using this toolbox, you can drag the SfCheckBox control to the XAML page. It will automatically install the required NuGet packages and add the namespace to the page. To install Syncfusion Xamarin Toolbox, refer to Toolbox.

Method 3: Adding SfCheckBox assemblies manually from the installed location

If you prefer to manually reference the assemblies instead referencing from NuGet, add the following assemblies in respective projects.

Location: {Installed location}/{version}/Xamarin/lib

PCL Syncfusion.Buttons.XForms.dll
Syncfusion.Core.XForms.dll
Syncfusion.Licensing.dll
Android Syncfusion.Buttons.XForms.dll
Syncfusion.Buttons.XForms.Android.dll
Syncfusion.Core.XForms.dll
Syncfusion.Core.XForms.Android.dll
Syncfusion.Licensing.dll
iOS Syncfusion.Buttons.XForms.dll
Syncfusion.Buttons.XForms.iOS.dll
Syncfusion.Core.XForms.dll
Syncfusion.Core.XForms.iOS.dll
Syncfusion.Licensing.dll
UWP Syncfusion.Buttons.XForms.dll
Syncfusion.Buttons.XForms.UWP.dll
Syncfusion.Core.XForms.dll
Syncfusion.Core.XForms.UWP.dll
Syncfusion.Licensing.dll
WPF Syncfusion.Buttons.XForms.dll
Syncfusion.Buttons.XForms.WPF.dll
Syncfusion.Core.XForms.dll
Syncfusion.Core.XForms.WPF.dll
Syncfusion.Licensing.dll

NOTE

To know more about obtaining our components, refer to these links for Mac and Windows.

IMPORTANT

Starting with v16.2.0.x, if you reference Syncfusion assemblies from the trial setup or from the NuGet feed, you also have to include a license key in your projects. Please refer to Syncfusion license key to know about registering Syncfusion license key in your Xamarin application to use our components.

NOTE

If you are adding the references from toolbox, this step is not needed.

Additional step for iOS

To launch SfCheckBox in iOS, call the SfCheckBoxRenderer.Init() in FinishedLaunching overridden method of AppDelegate class in iOS Project, as demonstrated in the following code example.

public override bool FinishedLaunching(UIApplication app, NSDictionary options)
{
    global::Xamarin.Forms.Forms.Init();
    LoadApplication(new App());
    Syncfusion.XForms.iOS.Buttons.SfCheckBoxRenderer.Init();
    return base.FinishedLaunching(app, options);
}

Additional step for UWP

This step is required only if the application is deployed in Release mode with .NET native tool chain enabled. It is for resolving the known Framework issue “Custom controls not rendering in Release mode” in UWP platform. Initializing the SfCheckBox assembly at OnLaunched overridden method of the App class in UWP project is the suggested work around, as demonstrated in the following code example.

protected override void OnLaunched(LaunchActivatedEventArgs e)
{
    ..... 
    rootFrame.NavigationFailed += OnNavigationFailed;
    // Add `using System.Reflection;` 
    List<Assembly> assembliesToInclude = new List<Assembly>();
    //Now, add all the assemblies that your app uses 
    assembliesToInclude.Add(typeof(SfCheckBoxRenderer).GetTypeInfo().Assembly);
    // replaces Xamarin.Forms.Forms.Init(e);
    Xamarin.Forms.Forms.Init(e, assembliesToInclude);
    ..... 
}

Additional step for WPF

To launch the check box in WPF, call the SfCheckBoxRenderer.Init() method in the MainWindow constructor of the MainWindow class after the Xamarin.Forms framework has been initialized and before the LoadApplication method is called as demonstrated in the following code sample.

public partial class MainWindow : FormsApplicationPage
{
     public MainWindow()
     { 
            InitializeComponent();
            
            Forms.Init();
            
            Syncfusion.XForms.WPF.Buttons.SfCheckBoxRenderer.Init();
            
            LoadApplication(new App());
     }
}

Create a Simple SfCheckBox

The SfCheckBox control is configured entirely in C# code or by using XAML markup. The following steps explain how to create a SfCheckBox and configure its elements.

Add namespace for referred assemblies

xmlns:syncfusion="clr-namespace:Syncfusion.XForms.Buttons;assembly=Syncfusion.Buttons.XForms"
using Syncfusion.XForms.Buttons;

Refer SfCheckBox control with declared suffix name for Namespace

<?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:GettingStarted"
	     xmlns:syncfusion="clr-namespace:Syncfusion.XForms.Buttons;assembly=Syncfusion.Buttons.XForms"             
	     x:Class="GettingStarted.MainPage">
    <ContentPage.Content>
        <StackLayout>
              <syncfusion:SfCheckBox x:Name="checkBox"/>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>
using Syncfusion.XForms.Buttons;
using Xamarin.Forms;
namespace GettingStarted
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            StackLayout stackLayout = new StackLayout();
            SfCheckBox checkBox = new SfCheckBox();
            stackLayout.Children.Add(checkbox);
            this.Content = stackLayout;
        }
    }
}

Setting caption

The check box caption can be defined using the Text property of SfCheckBox. This caption normally describes the meaning of the check box and it displays next to check box.

<syncfusion:SfCheckBox x:Name="checkBox" IsChecked="True" Text="CheckBox"/>
SfCheckBox checkBox = new SfCheckBox();
checkBox.IsChecked = true;
checkBox.Text = "CheckBox";

Xamarin.Forms CheckBox caption

Change the check box state

The three visual states of SfCheckBox are:

  • Checked
  • Unchecked
  • Indeterminate

Xamarin.Forms CheckBox states

You can change the state of the check box using the IsChecked property of SfCheckBox. In checked state, a tick mark is added to the visualization of check box.

State Property Value
checked IsChecked true
unchecked IsChecked false
indeterminate IsChecked null

NOTE

For the check box, to report the indeterminate state, set the IsThreeState property to true.

Check box can be used as a single or as a group. A single check box mostly used for a binary yes/no choice, such as “Remember me?”, login scenario, or a terms of service agreement.

<syncfusion:SfCheckBox x:Name="checkBox" Text="I agree to the terms of services for this site" IsChecked="True"/>
SfCheckBox checkBox = new SfCheckBox();
checkBox.Text = "I agree to the terms of services for this site";
checkBox.IsChecked = true;

Xamarin.Forms CheckBox tri-state

Multiple check boxes can be used as a group for multi-select scenarios in which a user chooses one or more items from the group of choices that are not mutually exclusive.

<Label x:Name="label" Text="Pizza Toppings" />
<syncfusion:SfCheckBox x:Name="pepperoni" Text="Pepperoni"/>
<syncfusion:SfCheckBox x:Name="beef" Text="Beef" IsChecked="True"/>
<syncfusion:SfCheckBox x:Name="mushroom" Text="Mushrooms"/>
<syncfusion:SfCheckBox x:Name="onion" Text="Onions" IsChecked="True"/>
Label label = new Label();
label.Text = "Pizza Toppings";
SfCheckBox pepperoni= new SfCheckBox();
pepperoni.Text = "Pepperoni";
SfCheckBox beef= new SfCheckBox();
beef.Text = "Beef";
beef.IsChecked = true;
SfCheckBox mushroom = new SfCheckBox();
mushroom.Text = "Mushrooms";
SfCheckBox onion = new SfCheckBox();
onion.Text = "Pepperoni";
onion.IsChecked = true;

Xamarin.Forms CheckBox multi-selection

Indeterminate

The SfCheckBox allows an indeterminate state in addition to the checked and unchecked state. The indeterminate state of the check box is enabled by setting the IsThreeState property of the control to True.

NOTE

When the IsThreeState property is set to False and IsChecked property is set to null then the check box will be in unchecked state.

The indeterminate state is used when a group of sub-choices has both checked and unchecked states. In the following example, the “Select all” checkbox has the IsThreeState property set to true. The “Select all” checkbox is checked if all child elements are checked, unchecked if all the child elements are unchecked, and indeterminate otherwise.

<syncfusion:SfCheckBox x:Name="selectAll" Text="Select All" IsChecked="{x:Null}" StateChanged="SelectAll_StateChanged"/>
<syncfusion:SfCheckBox x:Name="pepperoni" Text="Pepperoni" StateChanged="CheckBox_StateChanged"/>
<syncfusion:SfCheckBox x:Name="beef" Text="Beef" IsChecked="True" StateChanged="CheckBox_StateChanged"/>
<syncfusion:SfCheckBox x:Name="mushroom" Text="Mushrooms" StateChanged="CheckBox_StateChanged"/>
<syncfusion:SfCheckBox x:Name="onion" Text="Onions" IsChecked="True" StateChanged="CheckBox_StateChanged"/>
bool skip = false;
SfCheckBox selectAll, pepperoni, beef, mushroom, onion;
selectAll = new SfCheckBox();
selectAll.StateChanged += SelectAll_StateChanged;
selectAll.Text = "Select All";
pepperoni = new SfCheckBox();
pepperoni.StateChanged += CheckBox_StateChanged;
pepperoni.Text = "Pepperoni";
beef = new SfCheckBox();
beef.StateChanged += CheckBox_StateChanged;
beef.Text = "Beef";
beef.IsChecked = true;
mushroom = new SfCheckBox();
mushroom.StateChanged += CheckBox_StateChanged;
mushroom.Text = "Mushrooms";
onion = new SfCheckBox();
onion.StateChanged += CheckBox_StateChanged;
onion.Text = "Onions";
onion.IsChecked = true;

private void SelectAll_StateChanged(object sender, StateChangedEventArgs e)
{
    if (!skip)
    {
       skip = true;
       pepperoni.IsChecked = beef.IsChecked = mushroom.IsChecked = onion.IsChecked = e.IsChecked;
       skip = false;
    }
}

private void CheckBox_StateChanged(object sender, StateChangedEventArgs e)
{
    if (!skip)
    {
       skip = true;
       if (pepperoni.IsChecked.Value && beef.IsChecked.Value && mushroom.IsChecked.Value && onion.IsChecked.Value)
           selectAll.IsChecked = true;
       else if (!pepperoni.IsChecked.Value && !beef.IsChecked.Value && !mushroom.IsChecked.Value && !onion.IsChecked.Value)
	       selectAll.IsChecked = false;
       else
           selectAll.IsChecked = null;
       skip = false;
    }
}

Xamarin.Forms CheckBox intermediate state

This demo can be downloaded from this link.