QR Code Scanner In Xamarin.Forms

welcome everybody
I want a mobile application that reads QR and puts the result in an Entery box using xamarin.forms

I found a previous post in particular, but it did not work for me, and the reason is that this library does not exist  ---> 

1. using XFBarcode.Services;  
2. [assembly: Dependency(typeof(XFBarcode.Droid.Services.QrScanningService))]  
3. IQrScanningService

The error is as shown in the picture

Note: I just changed the name of the app

Can anyone help?