Under Review
Last Updated: 06 Jun 2025 16:24 by ADMIN
Nico
Created on: 04 Jun 2025 15:07
Category: CollectionView
Type: Bug Report
0
CollectionView: [iOS] NullReferenceException / App crash

I see iOS crashes in Sentry, seems like caused by clearing the RadCollectionView bound DataSource ObservableCollection, when an item was previously selected

Maui 9.0.70
Telerik 11.0

System.NullReferenceException: Arg_NullReferenceException
  ?, in void RadCollectionViewItemView.OnIsSelectedChanged()
  ?, in static RadCollectionViewItemView()+(BindableObject b, object o, object n) => { }
  ?, in void BindableObject.OnBindablePropertySet(BindableProperty property, object original, object value, bool didChange, bool willFirePropertyChanged)
  ?, in void Element.OnBindablePropertySet(BindableProperty property, object original, object value, bool changed, bool willFirePropertyChanged)
  ?, in void BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, object value, bool currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, bool silent)
  ?, in void BindableObject.SetValueCore(BindableProperty property, object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
  ?, in void BindableObject.SetValue(BindableProperty property, object value)
  ?, in void RadCollectionViewItemView.set_IsSelected(bool value)
  ?, in void RadCollectionView.SelectContainers(IEnumerable items, bool select)
  ?, in void RadCollectionView.SelectionHelperSelectionChanged(object sender, RadSelectionChangedEventArgs e)
  ?, in void <>c__DisplayClass36_0.<SelectionChangerSelectionChanged>b__0(?)+() => { }
  ?, in void ActiveSelectionScope.Dispose()
  ?, in void SelectionHelper.ClearSelection()
  ?, in void RadCollectionView.Telerik.Maui.Controls.ICollectionView.ItemsChanged(NotifyCollectionChangedEventArgs e)
  ?, in void CollectionViewModel.OnDataProviderViewChanged(object sender, ViewChangedEventArgs e)
  ?, in void DataProviderBase.RaiseViewChanged(object sender, List<AddRemoveResult> changes, NotifyCollectionChangedEventArgs args, CollectionChange action, bool affectsAggregates)
  ?, in void LocalDataSourceProvider.ProcessCollectionChanged(NotifyCollectionChangedEventArgs e)
  ?, in void LocalDataSourceProvider.DataView_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
  ?, in void EnumerableDataSourceView.RaiseCollectionChanged(object sender, NotifyCollectionChangedEventArgs args)
  ?, in void EnumerableDataSourceView.ProcessCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
  ?, in void EnumerableDataSourceView.ProcessCollectionChangedOverride(object sender, NotifyCollectionChangedEventArgs args)
  ?, in void EnumerableDataSourceView.ProcessPendingCollectionChange()
  ?, in void DataProviderBase.RaiseViewChanging(object sender, IList changedItems, CollectionChange action)
  ?, in void LocalDataSourceProvider.DataView_CollectionChanging(object sender, NotifyCollectionChangedEventArgs e)
  ?, in void EnumerableDataSourceView.HandleCollectionChangedOverride(object sender, NotifyCollectionChangedEventArgs e)
  ?, in void EnumerableDataSourceView.Telerik.Maui.IWeakEventListener.ReceiveEvent(object sender, object args)
  ?, in void WeakEventHandlerList<NotifyCollectionChangedEventArgs>.ProcessEvent(object sender, object args)
  ?, in void WeakEventHandlerList<NotifyCollectionChangedEventArgs>.OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
  ?, in void ObservableCollection<ViewBundle>.OnCollectionChanged(NotifyCollectionChangedEventArgs)
  ?, in void ExtObservableCollection<ViewBundle>.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
  ?, in void ObservableCollection<ViewBundle>.OnCollectionReset()
  ?, in void ObservableCollection<ViewBundle>.ClearItems()
  ?, in void ExtObservableCollection<ViewBundle>.ClearItems()
  ?, in void Collection<ViewBundle>.Clear()
  ?, in void SearchViewViewModel.Dispose(bool disposing)
  ?, in void PropertyChangedNotifyingBase.Dispose()
  ?, in async void ViewBundle.Dispose(bool disposing)
  ?, in void <>c.<ThrowAsync>b__128_0(?)+(object state) => { }
  ?, in void NSAsyncSynchronizationContextDispatcher.Apply()
  ?, in void __Registrar_Callbacks__.callback_3311_Foundation_NSAsyncSynchronizationContextDispatcher_Apply(IntPtr pobj, IntPtr sel, IntPtr* exception_gchandle)

3 comments
ADMIN
Didi
Posted on: 06 Jun 2025 16:24

Hi Nico,

Thank you for all details shared.

With Telerik MAUI 11.0.0 version, we have introduced the screen reader support on iOS and Android for CollectionView. Could you please share whether you have the selecteditem(s) properties set? Also how yo clear the items, setting a new collection or just call Clear method? Share more details on this. 

Could you please downgrade to Telerik MAUI 10.1.0 and test on your side whether the crash will occur.

Looking forward to your reply.

Regards,
Didi
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Nico
Posted on: 06 Jun 2025 09:01
I can reproduce this in my production app. If there's a test build/build with logging, I'd be happy to test it.
Nico
Posted on: 05 Jun 2025 13:23

Revert "Add Accessibility Selected for iOS CollectionView (#29014)" by PureWeen · Pull Request #29827 · dotnet/maui

In MAUI there is code going to be reverted
I see you added similar code in OnIsSelectedChanged in 11.0