Xamarin.Tip – No Bounce ScrollView in Xamarin.Forms

So on iOS, UIScrollView bounces by default so in Xamarin.Forms the ScrollView natrually bounces. But what if you don’t want your ScrollView to bounce? Android doesn’t bounce, so we won’t worry about it.

Let’s solve this problem with a custom renderer and control called NoBounceScrollView. This could also be done with an Effect but I like to have a custom control with the verbosity and flexibility with a renderer.

Let’s start by building a simple control in our Xamarin.Forms project:

NoBounceScrollView.cs

public class NoBounceScrollView : ScrollView { }

We don’t need anything in it since we are just going to assume it should never bounce and doesn’t affect the ScrollView in any other way. If you want, you can add a bindable property here to set Bouncable or something like that to true or false. Note: if you don’t want your ScrollView to bounce ever, then you don’t need this. Instead just have your renderer replace the default ScrollView renderer.

So we have our Xamarin.Forms control to build the renderer for, so now let’s create the iOS renderer:

NoBounceScrollViewRenderer.cs

public class NoBounceScrollViewRenderer : ScrollViewRenderer
{

    protected override void OnElementChanged(VisualElementChangedEventArgs e)
    {
        base.OnElementChanged(e);
        UpdateScrollView();
    }

    private void UpdateScrollView()
    {
        ContentInset = new UIKit.UIEdgeInsets(0, 0, 0, 0);
        if (UIDevice.CurrentDevice.CheckSystemVersion(11, 0))
            ContentInsetAdjustmentBehavior = UIKit.UIScrollViewContentInsetAdjustmentBehavior.Never;
        Bounces = false;
        ScrollIndicatorInsets = new UIKit.UIEdgeInsets(0, 0, 0, 0);
    }
}

What this is doing is setting the content insets to 0 so we don’t have empty space on top or bottom that the bouncing adds, and we also set Bounces to false. Note that the ContentInsetAdjustmentBehavior is only available on iOS 11 and higher, so for that extra step, we need to check the current iOS version.

Lastly, be sure to register your renderer:

[assembly: ExportRenderer(typeof(NoBounceScrollView), typeof(NoBounceScrollViewRenderer))]

or if you are replacing all ScrollViews:

[assembly: ExportRenderer(typeof(ScrollView), typeof(NoBounceScrollViewRenderer))]

Now we have everything we need! So let’s use it in our page:

MainPage.xaml

<ContentPage ...>
    <components:NoBounceScrollView>
        <StackLayout>
            ...
        </StackLayout>
    </components:NoBounceScrollView>
</ContentPage>

Check out the difference!

You can see this control in action with the EF Go Ahead Tours Companion App


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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3 thoughts on “Xamarin.Tip – No Bounce ScrollView in Xamarin.Forms”

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