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Simultaneous Pan Gesture Recognition on iOS

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When a PanGestureRecognizer is attached to a view inside a scrolling view, all of the pan gestures are captured by the PanGestureRecognizer and aren't passed to the scrolling view. Therefore, the scrolling view will no longer scroll.

This iOS platform-specific enables a PanGestureRecognizer in a scrolling view to capture and share the pan gesture with the scrolling view. It's consumed in XAML by setting the Application.PanGestureRecognizerShouldRecognizeSimultaneously attached property to true:

<Application ...
             xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
             ios:Application.PanGestureRecognizerShouldRecognizeSimultaneously="true">
    ...
</Application>

Alternatively, it can be consumed from C# using the fluent API:

using Xamarin.Forms.PlatformConfiguration;
using Xamarin.Forms.PlatformConfiguration.iOSSpecific;
...

Xamarin.Forms.Application.Current.On<iOS>().SetPanGestureRecognizerShouldRecognizeSimultaneously(true);

The Application.On<iOS> method specifies that this platform-specific will only run on iOS. The Application.SetPanGestureRecognizerShouldRecognizeSimultaneously method, in the Xamarin.Forms.PlatformConfiguration.iOSSpecific namespace, is used to control whether a pan gesture recognizer in a scrolling view will capture the pan gesture, or capture and share the pan gesture with the scrolling view. In addition, the Application.GetPanGestureRecognizerShouldRecognizeSimultaneously method can be used to return whether the pan gesture is shared with the scrolling view that contains the PanGestureRecognizer.

Therefore, with this platform-specific enabled, when a ListView contains a PanGestureRecognizer, both the ListView and the PanGestureRecognizer will receive the pan gesture and process it. However, with this platform-specific disabled, when a ListView contains a PanGestureRecognizer, the PanGestureRecognizer will capture the pan gesture and process it, and the ListView won't receive the pan gesture.