在iPhone上将utf-8 std::string转换为std::wstring

I have a UTF-8 string (created an std::string from a byte array) I understand that the encoding means that the size()/length() won't give me the actual number of glyphs if the text is chinese for instance... I understand that in order to get the unicode character code of each glyph I need to convert it to wstring (or any UTF>8 representation) and then I can get the value that will represent what I want.I have a UTF-8 string (created an std::string f