Strings only work when it's a literal?

[alexisbronchart]

I'm trying this and getting this error:

Is this a bug or does it work only with literals?

[mattt]

Your example constructs a dictionary with String keys and AnyEncodable values. Like the compiler error says, you can't put a String value where an AnyEncodable value is expected. The reason string literals work is that AnyEncodable AnyEncodable conforms to ExpressibleByStringLiteral; in this context, string literals result in AnyEncodable values, not String.

You can convert a String to AnyEncodable using string interpolation (as you have in the next line of your example) or through an explicit initializer (AnyEncodable(bar)).