Latest Telerik components are not building in Xamarin 5

[Krishna]

We had a Xamarin 3 iOS application built using Telerik 2018 components and it was working fine until the recent update in iOS. However, after the iOS update to 15, Xamarin 3 iOS app started crashing. Then we updated our app to Xamarin 5 and were able to successfully compile and run it on an iOS 15 simulator. But the Telerik 2018 controls did not render on screen. So we upgraded Telerik control to 2021 version (trial), and now we are having following error which broke the compilation of the entire project.

you must add a reference to assembly 'netstandard version=2.0.0.0 xamarin

It seems that Telerik 2021 controls have a dependency on netstandard library which is either not supported or cannot be installed from NuGet. 

It would be great if you could help us to resolve this issue. This way we would recover our app from crashes, and purchase the latest updates for Telerik.

[Didi]

Hello,

Since R2 2019 version of Telerik UI for Xamarin, it requires SkiaSharp 1.68.0. The error you are observing is because the SkiaSharp v 1.68.0 does not support PCL projects. The last version that supports it is v1.60.0. More details about this can be found at the following link from the SkiaSharp GitHub repo https://github.com/mono/SkiaSharp/issues/541  

Explanation can be found here: https://github.com/mono/SkiaSharp/issues/541#issuecomment-393519086  

Solution:

1) Migrate from PCL to .NET Standard 
How to do that, check following links that might be helpful:

Upgrade from PCL to .NET Standard topic and How to convert PCL to .NET Standard

2)  PCL project
If you really need to support PCL, then you could try using versions of Telerik UI for Xamarin before 2018.2.821.250.

I suggest you migrate the project to .NET Standard as based on the Microsoft documentation: Portable Class Libraries (PCLs) are considered deprecated in the latest versions of Visual Studio. 

Using .NET Standard project you can use the latest versions of Telerik UI for Xamarin, Xamarin.Forms and SkiaSharp with all fixes and new features included.

Regards,
Didi
Progress Telerik