Linking Error When Running on Device about xamarin.swift

[Flash3001]

Hey @bwalpoleuk, most likely your library was built using a different version of Xcode.

You can check that by opening the YOURLIBRARY-Swift.h file inside the framework and looking at the header, it says which version of Swift was used to compile. Then you can check your installed version by typing swift --version on your terminal (Swift 4.2.1 as it is the one that comes with Xcode 10.1).

If that is the case you have 2 options:
1 - Recompile your library using Xcode 10.1 and rebuild the binding.
2 - downgrade Xcode and the matching Swift packages on your Xamarin project.

Side note: You can remove all your Swift4 packages and replace with the https://www.nuget.org/packages/Xamarin.Swift/ as one of the benefits is that it does this exact check for you at compile time so you know beforehand if library and Xcode doesn't match.

[bwalpoleuk]

@Flash3001 It appears to have been built using Swift 5

// Generated by Apple Swift version 5.0 (swiftlang-1001.0.69.5 clang-1001.0.46.3)

Unfortunately its a 3rd party library so re-compiling it isn't an option.

[Flash3001]

It is even better, Swift 5 brings a lot of good changes. You can update your Xcode to 10.2 (or 10.2.1) and install the new Xamarin.Swift package (single package) - please be sure to test on iOS 11, if you only test on iOS 12.2 you can miss some issues.

[bwalpoleuk]

Great! That fixed it, removing all the Swift 4 packages and installing the new single package https://www.nuget.org/packages/Xamarin.Swift/