System.String in UWP

Question

From where does the reference of the System.String is being done in UWP application projects?

I got this question as I have a String.Replace method option Replace(String, String, StringComparison) in any Android app projects which is referring in Xamarin.Android and same way in iOS app project referring Xamarin.iOS as well.

But, in case of UWP, I am not able to get the same behaviour of String.Replace

EDIT :

Adding to the question based on the comment that UWP is using .NET Core, is there is any documentation on which .NET Core version each of the UWP/Windows SDK version is using? Because, this option of String.Replace is something new in .NET Core 2.0 and above as I can understand from Microsoft Docs of the same as quoted above in link.

Answer 1

Based on some trials, what I can understand is UWP is using .NET core internally for some things at least from Fall Creators Update (16299) of UWP SDK .

The above mentioned way of String.Replace() function signature is something available in a project which is targeting UWP SDK version of Fall Creators Update (16299), but not any SDK version below that.

But, .NET Core reference of UWP SDK is not something I could see anywhere officially mentioned in docs by Microsoft.