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[iOS] NullReferenceException when navigating away or switching tabs with Xamarin.Forms 3.3.0.912540
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Jeremy
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Jeremy asked on 22 Oct 2018, 07:42 PM

Also posted here:

https://feedback.telerik.com/Project/168/Feedback/Details/258349-ios-datagrid-causes-nullreferenceexception-when-navigating-away

And here:

https://github.com/xamarin/Xamarin.Forms/issues/4178

Looks like there was a regression sometime between Xamarin.Forms 3.2.0.839982 and version 3.3.0.912540 with the DataGrid. After a DataGrid becomes visible on a page (or just on a page that becomes visible, even if the DataGrid itself is set to IsVisible = false), a NullReferenceException occurs if you navigate away or switch tabs in a RadTabView. Seems to only happen on iOS, and started happening when I upgraded from Xamarin.Forms from 3.2.0.839982 to version 3.3.0.912540. Possibly a Xamarin.Forms bug and not a Telerik bug.

In case anyone else has the same issue, the workaround for me is just to go back to Xamarin.Forms 3.2.0.839982 (not sure if the issue occurs in the other 3.2.* version in between). 

 

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Lance | Manager Technical Support
Telerik team
answered on 22 Oct 2018, 08:28 PM
Hi Jeremy,

This is occurring because of a bug in Xamarin.Forms 3.3, we have opened an issue with Microsoft and the Xamarin team has already worked on a fix. You can follow this conversation on GitHub here: https://github.com/xamarin/Xamarin.Forms/issues/4146

As you mentioned, the only workaround until Xamarin releases an update is to roll back to 3.2.

Regards,
Lance | Tech Support Engineer, Sr.
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Desarrollo
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answered on 30 Nov 2018, 03:07 AM
Do you know if this is solved on 3.4?
I'm working with 3.3.0.967583 but when the tab is selected, I get the null on iOS. Android is working good
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Desarrollo
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answered on 30 Nov 2018, 03:16 AM

I just check the releases notes on 3.3.0.967583 and they said that is fixed but the problem is still there

https://developer.xamarin.com/releases/xamarin-forms/xamarin-forms-3.3/

Github #4146 - "iOS: NullReferenceException is thrown when setting the element of the renderer to null after upgrading to 3.3" (#4179)

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Yana
Telerik team
answered on 03 Dec 2018, 03:10 PM
Hello Ernesto,

I have just checked the setup with DataGrid that raised the exception with 3.3.0.967583 and it seems resolved.  I have attached my test app, could you download it and test it on your side?  What are the differences from the scenario you have?

I'm looking forward to your reply.

Regards,
Yana
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Desarrollo
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answered on 04 Dec 2018, 08:05 PM

Hi Yana, i found that the GroupDescriptor is giving me the null exception

<telerikGrid:RadDataGrid.GroupDescriptors>
                        <telerikData:PropertyGroupDescriptor PropertyName="**FIELD**"  />
</telerikGrid:RadDataGrid.GroupDescriptors>

I comment this code and the app start to work, can you check please

 

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Desarrollo
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answered on 04 Dec 2018, 08:13 PM
BTW, i'm using xamarin forms 3.3.0.967583 and the Telerik UI for Xamarin R3 2018 (the latest one)
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Desarrollo
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answered on 04 Dec 2018, 08:27 PM
BTW, i'm using xamarin forms 3.3.0.967583 and the Telerik UI for Xamarin R3 2018 (the latest one)
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Desarrollo
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answered on 04 Dec 2018, 09:20 PM
Solved! it was a resource declaration on the iOS info.plist
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Yana
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answered on 05 Dec 2018, 10:55 AM
Hi Ernesto,

Thank you for the follow-up. I am glad to hear you've managed to resolve it.

Regards,
Yana
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Jeremy
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Answers by
Lance | Manager Technical Support
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Desarrollo
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Yana
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