Xamarin Forms Creating Custom Views and Controls Step by step Implementation and Top 10 Questions and Answers

Last Update: April 01, 2025 20 mins read Difficulty-Level: beginner

Creating Custom Views and Controls in Xamarin.Forms: A Detailed Guide

Xamarin.Forms is a powerful framework that allows developers to create cross-platform mobile applications for iOS, Android, and Windows, using a single shared codebase. As the demands of mobile application development grow, it often becomes necessary to create custom views and controls to meet specific design and functionality requirements. This guide will walk you through the process of creating custom views and controls in Xamarin.Forms, providing you with the essential information and step-by-step instructions needed to get started.

Understanding Xamarin.Forms Customization

Before diving into creating custom views and controls, it’s important to understand the fundamental components of Xamarin.Forms and how they can be extended to achieve desired customization. Here's a brief overview:

Custom Renderers: These are used to override the default rendering of a control on a platform-specific level. This allows you to customize the appearance and behavior of a control across all platforms (iOS, Android, UWP) separately.
Effects: These are reusable pieces of code that modify the appearance or behavior of controls. Effects are platform-independent and can be used to enhance existing controls with additional functionality.
Custom Views: These are entirely new controls created from scratch that extend existing Xamarin.Forms elements or use platform-specific controls directly.
Custom Layouts: Layouts manage the positioning of controls within a view. Custom layouts can be created to handle unique layout requirements that cannot be met by the built-in layouts.

Step-by-Step Guide to Creating a Custom Control

Let’s walk through the process of creating a simple custom control—a progress bar that displays a color gradient based on the progress percentage.

1. Define the Custom Control:

Create a new class that inherits from an existing Xamarin.Forms control. For our example, we will inherit from BoxView since it provides simple drawing capabilities.

public class GradientProgressBar : BoxView
{
    public static readonly BindableProperty ProgressProperty =
        BindableProperty.Create(nameof(Progress), typeof(double), typeof(GradientProgressBar), 0.0);

    public double Progress
    {
        get => (double)GetValue(ProgressProperty);
        set => SetValue(ProgressProperty, value);
    }
}

2. Implement Custom Rendering (iOS):

Create a custom renderer for iOS that overrides the default rendering logic of the GradientProgressBar. This involves creating a subclass of BoxRenderer and using platform-specific APIs to draw the gradient.

[assembly: ExportRenderer(typeof(GradientProgressBar), typeof(GradientProgressBarRenderer))]
namespace YourName.iOS
{
    public class GradientProgressBarRenderer : BoxRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<BoxView> e)
        {
            base.OnElementChanged(e);

            if (Control == null) return;

            UpdateGradient();
        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);

            if (e.PropertyName == nameof(GradientProgressBar.Progress))
            {
                UpdateGradient();
            }
        }

        void UpdateGradient()
        {
            if (Element == null) return;

            using (var gradient = new CAGradientLayer())
            {
                gradient.Frame = Control.Bounds;
                gradient.Colors = new CGColor[] 
                { 
                    UIColor.Red.CGColor, 
                    UIColor.Green.CGColor 
                };

                var progress = (Element as GradientProgressBar).Progress;
                gradient.StartPoint = new CGPoint(0, 0);
                gradient.EndPoint = new CGPoint(progress, 0);

                Control.Layer.InsertSublayer(gradient, 0);
            }
        }
    }
}

3. Implement Custom Rendering (Android):

Similar to the iOS renderer, create a custom renderer for Android that overrides the default rendering logic. This involves creating a subclass of BoxRenderer and using platform-specific APIs to draw the gradient.

[assembly: ExportRenderer(typeof(GradientProgressBar), typeof(GradientProgressBarRenderer))]
namespace YourName.Droid
{
    public class GradientProgressBarRenderer : BoxRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<BoxView> e)
        {
            base.OnElementChanged(e);

            if (Control == null)
            {
                SetBackgroundColor(global::Android.Graphics.Color.Transparent);
            }

            UpdateGradient();
        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);

            if (e.PropertyName == nameof(GradientProgressBar.Progress))
            {
                UpdateGradient();
            }
        }

        void UpdateGradient()
        {
            var progress = (Element as GradientProgressBar).Progress;
            var progressWidth = (int)(Width * progress);

            var layerDrawable = new GradientDrawable(GradientDrawable.Orientation.LeftRight,
                new int[] { Color.Red, Color.Green });

            var clipDrawable = new ClipDrawable(layerDrawable, GravityFlags.Left, ClipDrawableOrientation.Horizontal);

            Control.SetBackground(clipDrawable.Draw(drawable => {
                drawable.SetBounds(0, 0, progressWidth, Height);
            }));
        }
    }
}

4. Using the Custom Control:

Once the custom control and its renderers are implemented, you can use the GradientProgressBar in your XAML or code-behind files as you would any other Xamarin.Forms control.

<local:GradientProgressBar Progress="0.5" WidthRequest="200" HeightRequest="20" />

Best Practices for Custom Controls

Reusability: Design custom controls to be reusable across multiple pages and projects. Encapsulate behavior and styling within the control itself.
Performance: Efficiently manage drawing operations and avoid unnecessary redraws. Use caching and other performance optimizations where possible.
Accessibility: Ensure that custom controls are accessible to all users, including those relying on accessibility features. Implement appropriate accessibility properties and behaviors.
Maintainability: Write clear, well-documented code that is easy to maintain and extend. Use consistent naming conventions and structure.
Testing: Thoroughly test custom controls on all target platforms to ensure consistent performance and appearance.

Conclusion

Creating custom views and controls in Xamarin.Forms is a powerful way to enhance the design and functionality of your mobile applications. By understanding the different components of customization and following best practices, you can create reusable, performant, and accessible controls that meet your unique requirements. Whether you're a beginner or an experienced developer, the ability to create custom controls is an essential skill in the world of mobile app development. Happy coding!

Xamarin.Forms Creating Custom Views and Controls: Step-by-Step Guide for Beginners

Creating custom views and controls in Xamarin.Forms provides extensive flexibility and allows developers to tailor the UI to fit their specific needs. Whether you're looking to enhance the functionality of existing controls or develop unique interfaces for your applications, understanding how to create custom controls will greatly benefit your app's development process. In this guide, we'll walk through the steps to create a custom control, set a route in your application, and run the application to see data flow in action. This will be a beginner's guide, so let's get started!

1. Setting Up Your Xamarin.Forms Project

Before we start with the actual creation of a custom control, make sure you have Xamarin.Forms installed. You can create a new Xamarin.Forms project by following these steps:

Open Visual Studio and click on "Create a new project".
Select "Xamarin.Forms App" template.
Name your project, e.g., "CustomControlDemo", and click "Create".
In the next window, choose the project template. Select "Blank" and ensure that the platform targets "Android" and "iOS".
Click "Create" again to set up your project.

2. Creating a Custom Control

Let's create a simple custom control—a custom button that changes its background color when clicked.

Step 2.1: Create a Custom View

Right-click on the "Pages" folder in your .NET Standard project (e.g., CustomControlDemo).
Select "Add" > "New Item".
Choose "Class" and name it CustomButton.cs.
Replace the default code with the following:

using Xamarin.Forms;

namespace CustomControlDemo
{
    public class CustomButton : Button
    {
        // Constructor to set default properties
        public CustomButton()
        {
            Text = "Click Me!";
            BackgroundColor = Color.Blue;
            TextColor = Color.White;
        }

        protected override void OnClicked()
        {
            base.OnClicked();

            // Toggle background color on click
            if (BackgroundColor == Color.Blue)
            {
                BackgroundColor = Color.Green;
            }
            else
            {
                BackgroundColor = Color.Blue;
            }
        }
    }
}

3. Registering the Custom Control in XAML

To use the custom control in your XAML pages, you need to register it first.

Open the MainPage.xaml file.
At the top of the file, add the namespace for your custom control:

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:CustomControlDemo"
             x:Class="CustomControlDemo.MainPage">

Inside the ContentPage, add the CustomButton control:

<ContentPage.Content>
    <StackLayout>
        <local:CustomButton/>
    </StackLayout>
</ContentPage.Content>

4. Setting Up Navigation for Custom Control

Let's create another page that will be navigated to when the button is clicked.

Step 4.1: Create a New Page

Right-click on the Pages folder in your .NET Standard project.
Select "Add" > "New Item".
Choose "Content Page" and name it SecondPage.xaml.
Leave the default code and click "Add".

Step 4.2: Update the CustomButton to Navigate

Go back to CustomButton.cs.
Modify the OnClicked method to include navigation logic:

using Xamarin.Forms;

namespace CustomControlDemo
{
    public class CustomButton : Button
    {
        public CustomButton()
        {
            Text = "Click Me!";
            BackgroundColor = Color.Blue;
            TextColor = Color.White;
        }

        protected override void OnClicked()
        {
            base.OnClicked();

            // Toggle background color on click
            if (BackgroundColor == Color.Blue)
            {
                BackgroundColor = Color.Green;
            }
            else
            {
                BackgroundColor = Color.Blue;
            }

            // Navigate to SecondPage
            Navigation.PushAsync(new SecondPage());
        }
    }
}

5. Running the Application

Now, let's run our application and see the custom control in action!

Step 5.1: Set the MainPage to Use Navigation

Open App.xaml.cs in your .NET Standard project.
Modify the App constructor to set up a navigation page:

using Xamarin.Forms;

namespace CustomControlDemo
{
    public partial class App : Application
    {
        public App()
        {
            InitializeComponent();

            // Set MainPage to a NavigationPage with MainPage set to MainPage.xaml
            MainPage = new NavigationPage(new MainPage());
        }
    }
}

Step 5.2: Run the Application

Set your target platform either Android or iOS.
Click on the "Start" button in Visual Studio or press F5 to run your application.
Once the app is running, you should see the custom button on the MainPage.
Click the button, and you should see the background color change and navigate to the SecondPage.

6. Observing Data Flow

Even though we have a simple application, understanding data flow in this context is important. The CustomButton class is handling the button's click event and changing the background color. Additionally, it uses the Navigation service to move from MainPage to SecondPage.

7. Conclusion

In this guide, we covered the creation of a custom control in Xamarin.Forms, set up navigation between pages, and ran the application to observe the data flow. You can extend this simple concept to build more complex custom controls and navigate more efficiently within your Xamarin.Forms applications. Happy coding!

By following these steps, you will have not only created a custom control but also understood how to integrate it into your Xamarin.Forms application and manage navigation between pages.

Top 10 Questions and Answers on Creating Custom Views and Controls in Xamarin.Forms

Xamarin.Forms is a powerful tool for building cross-platform mobile applications, allowing developers to write code once and run it on multiple platforms seamlessly. However, sometimes you will need to create custom views and controls that are not available out of the box. Here are ten frequently asked questions (FAQs) and their comprehensive answers on creating custom views and controls in Xamarin.Forms.

1. What are the reasons to create custom views and controls in Xamarin.Forms?

Answer: Creating custom views and controls in Xamarin.Forms can serve several purposes:

Branding and Consistency: Ensuring the UI aligns with the brand identity and maintains consistency across the application.
Functionality: Providing specialized features that Xamarin.Forms standard controls cannot offer.
Performance: Custom controls can optimize rendering and performance for specific tasks, such as intensive animations or complex UI elements.
Code Reusability: Crafting reusable components that can be shared across multiple projects, reducing duplication of effort.
Enhancement of User Experience: Delivering a unique and enhanced user experience tailored to your application’s requirements.

2. What is the difference between custom renderers and custom views in Xamarin.Forms?

Answer: In Xamarin.Forms, the distinction between custom renderers and custom views is crucial for understanding how UI components are customized:

Custom Renderers: Customize the look and behavior of an existing Xamarin.Forms control on each platform using platform-specific code. This approach is ideal for modifying built-in controls like buttons, labels, or layouts.
Custom Views: Create entirely new UI components from scratch or extend existing controls by adding new properties or methods, which can be used across different platforms. Custom views are necessary when you need functionality or appearance that does not exist in the standard controls.

3. How do I create a simple custom control in Xamarin.Forms?

Answer: Creating a custom control in Xamarin.Forms involves several steps:

Create a New Class: Start by defining a new C# class that inherits from an existing Xamarin.Forms control, such as Button, ContentView, or View.

public class MyCustomButton : Button
{
    public MyCustomButton()
    {
        Text = "Custom Button!";
        BackgroundColor = Color.Blue;
        TextColor = Color.White;
    }
}

Add Custom Properties: Define bindable properties using BindableProperty to allow the control to be customized further.

public static readonly BindableProperty CustomColorProperty =
    BindableProperty.Create(
        propertyName: nameof(CustomColor),
        returnType: typeof(Color),
        declaringType: typeof(MyCustomButton),
        defaultValue: Color.Gray,
        propertyChanged: OnCustomColorChanged);

public Color CustomColor
{
    get => (Color)GetValue(CustomColorProperty);
    set => SetValue(CustomColorProperty, value);
}

private static void OnCustomColorChanged(BindableObject bindable, object oldValue, object newValue)
{
    var control = (MyCustomButton)bindable;
    control.BackgroundColor = (Color)newValue;
}

Use the Custom Control in XAML: Register the namespace and use the custom control in your XAML files.

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace"
             x:Class="YourNamespace.MainPage">

    <local:MyCustomButton CustomColor="Green" />

</ContentPage>

4. What are custom renderers, and how do I create one?

Answer: Custom renderers in Xamarin.Forms are platform-specific implementations of a Xamarin.Forms control. They are essential for modifying the appearance and behavior of controls on each platform.

Creating a Custom Renderer:

Create a Custom Control: Start by creating a custom Xamarin.Forms control.
```
public class CustomEntry : Entry { }
```

Define the Custom Renderer: In each platform-specific project (iOS, Android, UWP), create a renderer class that inherits from the base renderer for the control you are customizing.

iOS:

using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(CustomEntry), typeof(MyCustomEntryRenderer))]
namespace YourNamespace.iOS
{
    public class MyCustomEntryRenderer : EntryRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);

            if (Control != null)
            {
                Control.BackgroundColor = UIColor.Gray;
                Control.Layer.BorderColor = UIColor.White.CGColor;
                Control.Layer.BorderWidth = 2;
            }
        }
    }
}

Android:

using Android.Graphics;
using Android.Support.V7.Widget;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(CustomEntry), typeof(MyCustomEntryRenderer))]
namespace YourNamespace.Droid
{
    public class MyCustomEntryRenderer : EntryRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);

            if (Control != null)
            {
                Control.SetBackgroundColor(Android.Graphics.Color.Gray);
                Control.SetTextColor(Android.Graphics.Color.White);
                Control.SetPadding(10, 10, 10, 10);
            }
        }
    }
}

Use the Custom Renderer in XAML:

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace"
             x:Class="YourNamespace.MainPage">

    <local:CustomEntry Placeholder="Enter text..." />

</ContentPage>

5. Can I create custom views for specific platforms (iOS, Android, UWP) in Xamarin.Forms?

Answer: Yes, you can create custom views for specific platforms in Xamarin.Forms through platform-specific renderers or by utilizing platform-agnostic libraries that encapsulate platform-specific code.

Using Platform-Specific Libraries:

Add Platform-Specific Dependencies: Use NuGet to add libraries that provide the functionality you need.
```
dotnet add package Xamarin.Essentials
```

Access Platform-Specific Features: Use DependencyService to call platform-specific code from your shared project.

public interface IMyCustomView
{
    void DisplayCustomView();
}

iOS Implementation:

[assembly: Dependency(typeof(MyCustomViewiOS))]
namespace YourNamespace.iOS
{
    public class MyCustomViewiOS : IMyCustomView
    {
        public void DisplayCustomView()
        {
            // Implementation specific to iOS
        }
    }
}

Android Implementation:

[assembly: Dependency(typeof(MyCustomViewAndroid))]
namespace YourNamespace.Droid
{
    public class MyCustomViewAndroid : IMyCustomView
    {
        public void DisplayCustomView()
        {
            // Implementation specific to Android
        }
    }
}

Invoke Platform-Specific Code from Shared Code:

public void ShowMyCustomView()
{
    var myCustomView = DependencyService.Get<IMyCustomView>();
    myCustomView.DisplayCustomView();
}

6. How can I make my custom controls accessible to other developers?

Answer: Making your custom controls accessible to other developers involves creating a reusable, well-documented library. Here are the steps:

Organize Your Code: Create a separate project within your solution for the custom controls.

Define a NuGet Package: Convert your custom controls project into a NuGet package for easy distribution.

Create a .nuspec File: Define metadata about the package.

<?xml version="1.0"?>
<package >
  <metadata>
    <id>YourNamespace.CustomControls</id>
    <version>1.0.0</version>
    <title>YourNamespace Custom Controls</title>
    <authors>Your Name</authors>
    <owners>Your Name</owners>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <description>A set of custom controls for Xamarin.Forms.</description>
    <tags>xamarin, forms, custom, controls</tags>
  </metadata>
</package>

Build the Package: Use the nuget command-line tool to package your project.
```
nuget pack YourNamespace.CustomControls.csproj
```

Publish the Package: Upload your package to NuGet.org or a private NuGet feed.

nuget push YourNamespace.CustomControls.1.0.0.nupkg -Source nuget.org -ApiKey YOUR_API_KEY

Documentation: Provide comprehensive documentation, including installation instructions, usage examples, and API references.
Version Management: Use semantic versioning to manage and update your package.

7. How do I handle events in custom controls?

Answer: Handling events in custom controls involves defining and raising events in your custom control class, which can then be consumed by the parent page or view.

Define an Event in the Custom Control:

public class MyCustomButton : Button
{
    public event EventHandler CustomEvent;

    public MyCustomButton()
    {
        Clicked += (sender, e) => CustomEvent?.Invoke(this, EventArgs.Empty);
    }
}

Subscribe to the Event in XAML:

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace"
             x:Class="YourNamespace.MainPage">

    <local:MyCustomButton x:Name="myCustomButton" CustomEvent="HandleCustomEvent" />

</ContentPage>

Handle the Event in Code-Behind:

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
    }

    private void HandleCustomEvent(object sender, EventArgs e)
    {
        // Handle the custom event
    }
}

8. What are some best practices for creating custom controls in Xamarin.Forms?

Answer: Following best practices ensures that your custom controls are efficient, maintainable, and easy to use. Here are some recommendations:

Naming Conventions: Use clear and descriptive names for your custom controls and their properties to enhance code readability.
Reusability: Design your controls to be as generic as possible, allowing them to be reused across different projects and pages.
Performance Optimization: Optimize rendering and memory usage by avoiding unnecessary computations and minimizing layout changes.
Testing: Thoroughly test your custom controls on all supported platforms to ensure compatibility and performance.
Consistency: Maintain consistent behavior and appearance across different platforms by carefully defining custom renderers.
Documentation: Provide comprehensive documentation and examples to help other developers understand and use your controls.
Versioning: Use semantic versioning and maintain backward compatibility when updating your controls.
Error Handling: Implement robust error handling to manage exceptions and ensure smooth user experience.

9. How can I use third-party custom controls in my Xamarin.Forms project?

Answer: Using third-party custom controls in your Xamarin.Forms project involves several steps to integrate them seamlessly.

Find a Suitable Control: Search for a third-party custom control that meets your requirements. This can be done via NuGet, GitHub, or other developer resources.
Install the NuGet Package: Add the package to your Xamarin.Forms project using the NuGet package manager or the command-line tool.
```
dotnet add package PackageName
```

Add Namespaces in XAML: Include the namespace in your XAML files to access the custom controls.

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:thirdparty="clr-namespace:ThirdPartyNamespace;assembly=PackageName"
             x:Class="YourNamespace.MainPage">

    <thirdparty:CustomControl Property="Value" />

</ContentPage>

Configure and Use the Control: Follow the documentation provided by the third-party developer to configure and use the custom control effectively.
Handle Dependencies: If the custom control has additional dependencies, ensure they are properly installed and configured.

10. What are the common issues faced while creating custom controls, and how to resolve them?

Answer: Developing custom controls in Xamarin.Forms can present several challenges, but with careful planning and troubleshooting, most issues can be resolved.

Common Issues:

Platform-Specific Bugs: Custom controls may behave differently on each platform due to rendering differences.

Solution:
- Test thoroughly on all supported platforms.
- Implement custom renderers to handle platform-specific issues.
Performance Issues: Custom controls can lead to performance bottlenecks, especially if they perform complex operations.

Solution:
- Optimize rendering and memory usage.
- Use efficient algorithms and data structures.
Event Handling: Defining and handling events in custom controls can be complex.

Solution:
- Follow event handling best practices.
- Use EventArgs to pass data between the control and its consumers.
Compatibility: Custom controls may not work with certain versions of Xamarin.Forms or other libraries.

Solution:
- Check compatibility with library versions.
- Use version management tools like PackageReference to manage dependencies.
Documentation: Inadequate or unclear documentation can hinder the use of custom controls.

Solution:
- Provide comprehensive documentation with examples.
- Ensure documentation is up-to-date with any changes.

By addressing these challenges systematically, you can create robust and effective custom controls in Xamarin.Forms that enhance the functionality and user experience of your applications.