I am trying to call the
this IEnumerable<TSource> source
The compiler needs to implicitly convert a
string to an
Whether this works depends on the platform(s) you are targeting with the portable library and thus what subset of the .NET Framework is available. If you target .NET Framework 4 and for instance Xamarin, you have a different subset than if you were targeting .NET Framework 4.5.1 and Xamarin. In the former case, the compiler will reject an implicit cast from
IEnumerable<char>, while in the latter case it is accepted.
So the simple solution (if it is viable for you) would be to target .NET Framework 4.5.1 and higher. Otherwise, you may cast your string to a sequence of characters, e.g., using