This must be a real-newbie-level question (which is kind of embarassing having used plain TeX to write my PhD thesis in 1992), but I am not be able to find an answer. Even if there are 5 millions similar questions here... so, my MWE is this:
\documentclass{article}
\usepackage{fontspec}
\newfontfamily\dingbatsfont{Dingbats}
\newcommand\ding[1]{{\dingbatsfont\symbol{#1}}}
\begin{document}
\ding{115} % no output
{\dingbatsfont ❤} % error --- comment out to have a PDF file
\end{document}
...and running it with xelatex gives an error on the second line:
** WARNING ** 1 glyph names (out of 1) missing Unicode mapping.
** WARNING ** ToUnicode CMap "TZCCMX+Dingbats-UTF16" removed.
** ERROR ** pdf_ref_obj(): passed invalid object.
whilst if I remove it, I have no error, but the \ding{115} gives nothing. The strange thing is that the PDF file generated (when I remove the second line) seems to have the font loaded:
(0)samsung-romano:~/education/LibroEje/tmp% pdffonts lalla.pdf
name type encoding emb sub uni object ID
------------------------------------ ----------------- ---------------- --- --- --- ---------
IPQPDZ+Dingbats-Identity-H CID Type 0C Identity-H yes yes yes 5 0
WPNUQB+LMRoman10-Regular-Identity-H CID Type 0C Identity-H yes yes yes 7 0
...and the font is here and usable by LibreOffice:

I tried to substitute the 115 with the Unicode codepoint "2773 but then I have the error above again.
What am I doing (terribly) wrong?
\newfontface\myfont{Dingbats}instead of\font\myfonts="Dingbats"but then I have an error on\stepcounter... (??) – Rmano Oct 24 '13 at 14:29.pfbyou should better create a tfm-file and use it "in the standard" way and not with fontspec. – Ulrike Fischer Oct 24 '13 at 14:32