RadListView renderer throws NullReferenceException on device but not simulator

[Aaron]

Hi there,

I'm struggling to get the ListView working on my iOS devices. On the simulator these work fine, but on the devices i keep getting this error;

NullReferenceException: Object reference not set to an instance of an object

on the following line in my Main.cs file (same as the default xamarin one);

UIApplication.Main(args, null, "AppDelegate");

here's the stack trace

at Telerik.XamarinForms.DataControlsRenderer.iOS.ListView.UIListViewCell.UpdateSelectionViewStyle () [0x000b5] in <69c148d17a40435da18b2f1c1ff180c5>:0
at Telerik.XamarinForms.DataControlsRenderer.iOS.ListView.UIListViewCell.UpdateCell (Telerik.XamarinForms.DataControls.RadListView owner, System.Object dataItem) [0x0005a] in <69c148d17a40435da18b2f1c1ff180c5>:0
at Telerik.XamarinForms.DataControlsRenderer.iOS.ListViewDataSource.InitCell (TelerikUI.TKListView listView, Foundation.NSIndexPath indexPath, TelerikUI.TKListViewCell tkCell, Foundation.NSObject obj) [0x000f5] in <69c148d17a40435da18b2f1c1ff180c5>:0
at ObjCRuntime.Trampolines+SDActionArity4V1.Invoke (System.IntPtr block, System.IntPtr arg1, System.IntPtr arg2, System.IntPtr arg3, System.IntPtr arg4) [0x00033] in <9e260fcc0dbf47638fe447f503155067>:0
at (wrapper native-to-managed) ObjCRuntime.Trampolines+SDActionArity4V1:Invoke (intptr,intptr,intptr,intptr,intptr)

[Aaron]

further investigations; i can create a RadListView in XAML like so; and this works...

<dataControls:RadListView x:Name="customerListView"     BackgroundColor="White"                             IsPullToRefreshEnabled="True">

[Aaron]

Adding ItemsSource causes my application to crash as soon as the page starts to load....

 

<dataControls:RadListView x:Name="customerListView"
                                  ItemsSource="{Binding CustomerList}"
                                  BackgroundColor="White"
                                  IsPullToRefreshEnabled="True">

[Aaron]

Thrown Exception

stack trace

 

I can replicate this in my local development environment. For whatever reason as soon as I ask it to render (set ItemsSource) something it crashes with that error..

[Aaron]

https://slack-files.com/T06BQEKFZ-F3SHE5P7Z-a36f387da2

https://slack-files.com/T06BQEKFZ-F3RSHPD6W-6672946e91

 

this happens as soon as I set the ItemsSource property to something, and it tries to render a cell. If I dont set ItemsSource I can see the list view (i.e. i can pull down to refresh). Looks like a bug in the renderer code...

[Aaron]

https://slack-files.com/T06BQEKFZ-F3RSHPD6W-6672946e91

https://slack-files.com/T06BQEKFZ-F3SHE5P7Z-a36f387da2

[Tsvyatko]

Hello Aaron,

Thank you for contacting us! The reported issue seems to be related to a specific setting in debug build. You can try to uncheck incremental builds setting in project properties. Currently, mono has trouble loading all custom types when this setting is set. We are working to pinpoint and workaround the issue however it seems like a mono framework limitation.

We will update our documentation with troubleshooting article shortly as well as throw more meaningful exception.

Please, excuse us for the inconvenience caused.

Regards,
Tsvyatko
Telerik by Progress

[Sascha]

I had a similar NullReference exception, but not as detailed as the one posted here. But as suggested, building in release mode fixed it for me. Thanks for the hint.

[Marek]

I have incremental builds disabled in my Debug | iPhoneSimulator build configuration. The same exception appeared after updating controls to the current version - 2018.1.405.240

I already cleaned (manually) all bin/obj/packages folders and the issue remains:

at Telerik.XamarinForms.DataControlsRenderer.iOS.ListViewDataSource.OnDataChanged (System.Object sender, System.EventArgs eventArgs) [0x00000] in <50a3d3d8582c4c19be6c8f3aae71fce2>:0
 at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.RaiseDataChanged (Telerik.XamarinForms.Common.Data.CollectionChange change, Telerik.XamarinForms.DataControls.ListView.ListViewDataGroup group) [0x00012] in <50a3d3d8582c4c19be6c8f3aae71fce2>:0
 at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.RaiseDataChanged (Telerik.XamarinForms.Common.Data.CollectionChange change) [0x00000] in <50a3d3d8582c4c19be6c8f3aae71fce2>:0
 at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.OnStatusChanged (System.Object sender, Telerik.XamarinForms.Common.Data.DataProviderStatusChangedEventArgs eventArgs) [0x0002b] in <50a3d3d8582c4c19be6c8f3aae71fce2>:0
 at Telerik.XamarinForms.Common.Data.DataProviderBase.OnStatusChanged (Telerik.XamarinForms.Common.Data.DataProviderStatusChangedEventArgs args) [0x00038] in <aeb78dad1067408ca0f70679e60882f8>:0
 at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.ResetStatus () [0x00009] in <aeb78dad1067408ca0f70679e60882f8>:0
 at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.RefreshInternalView (System.Boolean resetStatus) [0x000b8] in <aeb78dad1067408ca0f70679e60882f8>:0
 at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.OnItemsSourceChanged (System.Object newValue) [0x00016] in <aeb78dad1067408ca0f70679e60882f8>:0
 at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.set_ItemsSource (System.Object value) [0x00010] in <aeb78dad1067408ca0f70679e60882f8>:0
 at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.UpdateItemsSource () [0x00011] in <50a3d3d8582c4c19be6c8f3aae71fce2>:0
 at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.OnPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs eventArgs) [0x00017] in <50a3d3d8582c4c19be6c8f3aae71fce2>:0
 at (wrapper delegate-invoke) <Module>.invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs)
 at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x0000a] in D:\agent\_work\1\s\Xamarin.Forms.Core\BindableObject.cs:146
 at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\agent\_work\1\s\Xamarin.Forms.Core\Element.cs:401
 at Telerik.XamarinForms.DataControls.RadListView.OnPropertyChanged (System.String propertyName) [0x00028] in <50a3d3d8582c4c19be6c8f3aae71fce2>:0
 at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00107] in D:\agent\_work\1\s\Xamarin.Forms.Core\BindableObject.cs:602
 at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\agent\_work\1\s\Xamarin.Forms.Core\BindableObject.cs:399
 at Xamarin.Forms.BindingExpression.ApplyCore (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property, System.Boolean fromTarget) [0x001f9] in D:\agent\_work\1\s\Xamarin.Forms.Core\BindingExpression.cs:172
 at Xamarin.Forms.BindingExpression.Apply (System.Boolean fromTarget) [0x0003e] in D:\agent\_work\1\s\Xamarin.Forms.Core\BindingExpression.cs:56
 at Xamarin.Forms.BindingExpression+BindingExpressionPart.<PropertyChanged>b__47_0 () [0x00000] in D:\agent\_work\1\s\Xamarin.Forms.Core\BindingExpression.cs:557
 at Foundation.NSAsyncActionDispatcher.Apply () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/11.10.1.178/src/Xamarin.iOS/Foundation/NSAction.cs:125

[Stephanos]

I am having the same problem as Marek, and I am using 2018.2.516. version.

I have a MasterDetailPage as the main page, and the RadListView is inside a content page which has been set as Detail for the main MasterDetailPage.

Everything works fine the first time, but when I set MasterDetailPage.Detail to some other page and set it back to the page that has RadListView on it, it generates NullReferenceException.

The following is my stacktrace:

  at Telerik.XamarinForms.DataControlsRenderer.iOS.ListViewDataSource.OnDataChanged (System.Object sender, System.EventArgs eventArgs) [0x00000] in <8f4a997bfc374486a1052675f6c6e0e8>:0 
  at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.RaiseDataChanged (Telerik.XamarinForms.Common.Data.CollectionChange change, Telerik.XamarinForms.DataControls.ListView.ListViewDataGroup group) [0x00012] in <8f4a997bfc374486a1052675f6c6e0e8>:0 
  at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.RaiseDataChanged (Telerik.XamarinForms.Common.Data.CollectionChange change) [0x00000] in <8f4a997bfc374486a1052675f6c6e0e8>:0 
  at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.OnStatusChanged (System.Object sender, Telerik.XamarinForms.Common.Data.DataProviderStatusChangedEventArgs eventArgs) [0x0002b] in <8f4a997bfc374486a1052675f6c6e0e8>:0 
  at Telerik.XamarinForms.Common.Data.DataProviderBase.OnStatusChanged (Telerik.XamarinForms.Common.Data.DataProviderStatusChangedEventArgs args) [0x00038] in <a2b7cf99c04e4c77b41c9475bb834c85>:0 
  at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.ResetStatus () [0x00009] in <a2b7cf99c04e4c77b41c9475bb834c85>:0 
  at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.RefreshInternalView (System.Boolean resetStatus) [0x000b8] in <a2b7cf99c04e4c77b41c9475bb834c85>:0 
  at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.OnItemsSourceChanged (System.Object newValue) [0x00016] in <a2b7cf99c04e4c77b41c9475bb834c85>:0 
  at Telerik.XamarinForms.Common.Data.LocalDataSourceProvider.set_ItemsSource (System.Object value) [0x00010] in <a2b7cf99c04e4c77b41c9475bb834c85>:0 
  at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.UpdateItemsSource () [0x00011] in <8f4a997bfc374486a1052675f6c6e0e8>:0 
  at Telerik.XamarinForms.DataControls.ListView.ListViewDataAdapter.OnPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs eventArgs) [0x00017] in <8f4a997bfc374486a1052675f6c6e0e8>:0 
  at (wrapper delegate-invoke) <Module>.invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs)
  at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x0000a] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:153 
  at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:402 
  at Telerik.XamarinForms.DataControls.RadListView.OnPropertyChanged (System.String propertyName) [0x00028] in <8f4a997bfc374486a1052675f6c6e0e8>:0 
  at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00116] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:634 
  at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:426 
  at Xamarin.Forms.BindingExpression.ApplyCore (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property, System.Boolean fromTarget) [0x00216] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:173 
  at Xamarin.Forms.BindingExpression.Apply (System.Boolean fromTarget) [0x0003e] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:57 
  at Xamarin.Forms.BindingExpression+BindingExpressionPart.<PropertyChanged>b__49_0 () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:612 
  at Foundation.NSAsyncActionDispatcher.Apply () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/11.10.1.178/src/Xamarin.iOS/Foundation/NSAction.cs:125 
  at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
  at UIKit.UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate) [0x00005] in /Library/Frameworks/Xamarin.iOS.framework/Versions/11.10.1.178/src/Xamarin.iOS/UIKit/UIApplication.cs:79 
  at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName)

[Marek]

@Stephanos if you need a workaround for this issue here it is:

 

01.public class MdRadListView : RadListView
02.{
03.    protected override void OnPropertyChanged(string propertyName = null)
04.    {
05.        try
06.        {
07.            base.OnPropertyChanged(propertyName);
08.        }
09.        catch (Exception ex)
10.        {
11.            // swallow or log if you wish
12.        }
13.    }
14.}

 

Although it's a nasty hack it works. It's sad that such hacks are normal part of working with Xamarin.Forms...

[Stefan Nenchev]

Hello, Marek, Stephanos,

We have identified this behavior and have it logged in our internal system. You can track the progress of the bug report on the following link - RadListView: [iOS] Exception when rebining ItemsSource after navigation. Actually, we are already working on the item and expect to have a fix with the service pack release which is planned for 20.06.2018. Please subscribe to the item so that you are automatically notified when the fix is applied.

Have a great rest of the week.

Regards,
Stefan Nenchev
Progress Telerik

[Fernando]

This error occurred to me using Visual Studio 2019 and the fix was to update to the last version the Visual Studio 2019 (Version 16.5.4) with this you will need to update the Mono too (Visual update ask to do that) in your Mac and those updates fix the problem.