Please note this is a breaking change if you're using EDN containing characters.
It's become clear that [NSNumber numberWithUnsignedChar] is not the correct ObjC mapping for EDN characters: e.g. other libraries such as a serialisation library we've encountered can generate these for small numbers. There's no way in this case to say the value should be encoded as a number not a unicode character, as shown by:
(lldb) po [@'a' class]
__NSCFNumber
(lldb) po [@((int8_t)97) class]
__NSCFNumber
(lldb) po [@'a' objCType]
"c"
(lldb) po [@((int8_t)97) objCType]
"c"
In this release, EDN characters are mapped to MPEdnCharacter, which is a simple wrapper around a unichar value.