[Tex/LaTex] How to insert a horizontal bar as a footnote at the end of a beamer slide in metropolis/mtheme

Question

In a beamer slide, using mtheme/metropolis theme, it is difficult to create a small horizontal bar at the bottom of the slide showing author name or inserting some different text for every slide.

An answer exists here. But the page numbering starts from the title page. How to make the numbering start from the slide after the title page?
And the ability to create a bar or some box around the footnotes would be excellent. Such bars exist by default in many different themes like the Madrid theme for beamer.

Answer 1

Based on https://tex.stackexchange.com/a/388811/36296

\documentclass{beamer}

\usetheme{metropolis}

\author{names}
\title{text}


\makeatletter
\def\beamer@autobreakframebox{%
  \global\setbox\beamer@splitbox=\box\voidb@x%
  \ifbeamer@autobreak%
    % Ok, frame was overful -> split it!
    \setbox\@tempboxa=\vsplit\beamer@framebox to\beamer@autobreakfactor\textheight%
    \global\setbox\beamer@splitbox=\box\beamer@framebox%
    \@tempdima=\ht\beamer@splitbox%
    \ifdim\@tempdima<\beamer@autobreaklastheight%
      \global\beamer@autobreaklastheight=\@tempdima\relax%
    \else%
      \setbox\@tempboxa=\vbox{\unvbox\@tempboxa\unvbox\beamer@splitbox}%
      \global\setbox\beamer@splitbox=\box\voidb@x%
    \fi%
    \setbox\beamer@framebox=\vbox to\textheight{\unvbox\@tempboxa%
      \vskip\beamer@framebottomskipautobreak%
      \ifvoid\beamer@splitbox%
              \begin{beamercolorbox}[wd=\paperwidth,left]{footnote}
                    \usebeamerfont{footnote}%   
                    \ifvoid\beamer@footins%
                        \vskip\baselineskip%
                    \else%
                        \unvbox \beamer@footins%
                        \global\setbox\beamer@footins=\box\voidb@x%
                    \fi%

                    \vskip-1.4\baselineskip%
                    \hspace{.5\paperwidth}%
                \parbox{.48\paperwidth}{%
                    \usebeamerfont{footnote}\strut\insertshortauthor\hfill\insertframenumber\quad%
                }%
              \end{beamercolorbox}%
      \fi%
      \beamer@exitcode%
    }%
  \else%
    \setbox\beamer@framebox=\vbox to\textheight{\unvbox\beamer@framebox%
      \vskip\beamer@framebottomskip%
              \begin{beamercolorbox}[wd=\paperwidth,left]{footnote}
                    \usebeamerfont{footnote}%   
                    \ifvoid\beamer@footins%
                        \vskip\baselineskip%
                    \else%
                        \unvbox \beamer@footins%
                        \global\setbox\beamer@footins=\box\voidb@x%
                    \fi%

                    \vskip-1.4\baselineskip%
                    \hspace{.5\paperwidth}%
                \parbox{.48\paperwidth}{%
                    \usebeamerfont{footnote}\strut\insertshortauthor\hfill\insertframenumber\quad%
                }%
              \end{beamercolorbox}%
      \beamer@exitcode}%
    \global\setbox\beamer@footins=\box\voidb@x%
  \fi%
  }
\makeatother

\setbeamerfont{footnote}{size=\scriptsize}
\setbeamertemplate{footline}{}
\setbeamercolor{footnote}{fg=white,bg=mDarkTeal}

\usepackage[style=authoryear]{biblatex}
\addbibresource{biblatex-examples.bib}

\begin{document}

\begin{frame}[plain,noframenumbering]
    \titlepage
\end{frame} 

\begin{frame}
   test
\end{frame} 

\begin{frame}
   test\footcite{bertram}

   text\footcite{angenendt}
\end{frame} 

\begin{frame}
    text\footcite{angenendt}
\end{frame} 

\begin{frame}
\printbibliography
\end{frame}

\end{document}