How to retrieve the expanding Accordion item index in Xamarin.Forms (SfAccordion)?

You can get the index of AccordionItem when expanding in Xamarin.Forms SfAccordion.

You can also refer the following article.

https://www.syncfusion.com/kb/11358/how-to-retrieve-the-expanding-accordion-item-index-in-xamarin-forms-sfaccordion

C#

You can get the index from the ExpandingAndCollapsingEventArgs of the Expanding event.

namespace AccordionXamarin.Behavior
{
    public class Behavior : Behavior<SfAccordion>
    {
        SfAccordion Accordion;
 
        protected override void OnAttachedTo(SfAccordion bindable)
        {
            Accordion = bindable;
            Accordion.Expanding += Accordion_Expanding;
            base.OnAttachedTo(bindable);
        }
 
        private void Accordion_Expanding(object sender, ExpandingAndCollapsingEventArgs e)
        {
            App.Current.MainPage.DisplayAlert("", "AccordionItem expanded at index " + e.Index, "Ok");
        }
    }
}