SfCarousel - cannot refresh ItemsSource collection on iOS because of ArgumentOutOfRangeException

Question

Hi,With v28.1.39 my ItemsSource is an ObservableCollection that can be refreshed with different items depending of the user choices.On iOS the first initialization of the collection works, but the second time, whenever I use new ObservableCollection<Item>(); or the .Clear(); method it throws an ArgumentOutOfRangeException.The 28.1.35 release notes says : Addressed an exception that occurred when dynamically clearing the SfCarousel ItemsSource collection on the iOS platform.If I rollback to 28.1.36 or 28.1.35 I still have the exception.Regards,Julien

Kamalesh Periyasamy · Accepted Answer

Hi Julien Barach,Thank you for
bringing this to our attention and providing the details of the behavior you
observed.We have reviewed the
issue you mentioned regarding the SfCarousel.SelectionChanged event being
triggered more frequently on iOS compared to Android, particularly when the
ItemsSource is cleared. As you noted, this discrepancy can lead to exceptions
being thrown on iOS when attempting to retrieve an item from an empty
ItemsSource.To address this, we
have made a modification to the sample code to ensure the ItemsSource count is
checked before accessing the selected item.

if (sender is
  Syncfusion.Maui.Carousel.SfCarousel sfCarousel &&
  sfCarousel.ItemsSource != null)
   { 
  var
  source = sfCarousel.ItemsSource as IList<Item>;
   if (source?.Count >
  sfCarousel.SelectedIndex) 
  {
        var selectedItem =
  sfCarousel.ItemsSource.ElementAt(sfCarousel.SelectedIndex) as Item;  
  }
  
  }

This ensures that
the code gracefully handles cases where the ItemsSource is empty, preventing
exceptions on iOS.Additionally, we
have taken your suggestion into consideration to align the behavior of the
SelectionChanged event across both Android and iOS platforms. Our team will
explore improvements to achieve consistent functionality across devices. Once
these enhancements are implemented, we will notify you or share the details
with you.We have also
attached the updated sample for your reference. Please check it and let us know
if it resolves the issue on your end.Regards,Kamalesh PAttachment: CarouselSample_2_780f144e.zip

Aarthi Arjunan · Answer

Hi Julien, We have reviewed
your query and created a sample based on your update. However, we were unable
to reproduce the reported issue. The ItemSource collection of the SfCarousel
was refreshed successfully without any exceptions. Additionally, we tested the
scenario with an empty collection, and it worked as expected. To better assist
you, could you please provide us with the complete code or a sample
demonstrating the issue with replication steps would be extremely helpful. This
will enable us to thoroughly investigate and propose a more accurate solution. For your
convenience, we have included the tested sample and a demonstration video as an
attachment. Please review the attached files and let us know if you have any
concerns. If necessary, please make any required modifications and share the
updated sample with us.  Please don’t
hesitate to contact us if you have any queries. Regards,Aarthi A.Attachment: Reference_d97d3f16.zip

Julien Barach · Answer

Hi,Your sample allowed me to identify precisely where the issue is.In fact it is the SfCarousel.SelectionChanged event that is too often triggered on iOS comparing to Android.My code for this event is something like this :if (sender is Syncfusion.Maui.Carousel.SfCarousel sfCarousel) {    var selectedItem = sfCarousel.ItemsSource.ElementAt(sfCarousel.SelectedIndex) as PictureModel;    _viewModel.SelectedCarouselItemChanged(selectedItem);}On iOS this event is triggered even when the ItemsSource is cleared, but not on Android. So the ElementAt method throws the exception on iOS because the ItemsSource is empty.I have updated your sample if you want to check.Now it's easy to fix on my side, but maybe you can improve things to get the same behavior on Android and iOS.Regards,JulienAttachment: CarouselSample_2_aac3a6c4.zip