Automatic frame titles and subtitles

Question

Is there a way to automatically use the section name as the frame title and the subsection name as the frame subtitle?

I think this question is related, but when I tried to hack that solution to change the substitution from \insertsubsectionhead to \insertsectionhead as follows, my frame title simply disappeared:

\addtobeamertemplate{frametitle}{
   \let\insertframetitle\insertsectionhead}{}

(later)

\section{Introduction}

\begin{frame}
   \frametitle{}

. . . 

Does it matter where that template manipulation appears? I have it in my preamble right after I choose my theme.

Bottom line: I have no idea how these internals work, so worst case I'll just continue duplicating the sections and subsection names into the frame titles and subtitles. I like the idea of keeping that connection back to the outline in every frame.

Answer 1

As the answer in the question you linked explains, it is not enough to add simply

\addtobeamertemplate{frametitle}{
   \let\insertframetitle\insertsectionhead}{}

this will work if you explicitly use a \frametitle{} command for each frame. The same answer explains how to avoid using the command explicitly by adding

\makeatletter
  \CheckCommand*\beamer@checkframetitle{\@ifnextchar\bgroup\beamer@inlineframetitle{}}
  \renewcommand*\beamer@checkframetitle{\global\let\beamer@frametitle\relax\@ifnextchar\bgroup\beamer@inlineframetitle{}}
\makeatother

So, in your case, you'll have to add the following lines to the preamble:

\addtobeamertemplate{frametitle}{
   \let\insertframetitle\insertsectionhead}{}
\addtobeamertemplate{frametitle}{
   \let\insertframesubtitle\insertsubsectionhead}{}


\makeatletter
  \CheckCommand*\beamer@checkframetitle{\@ifnextchar\bgroup\beamer@inlineframetitle{}}
  \renewcommand*\beamer@checkframetitle{\global\let\beamer@frametitle\relax\@ifnextchar\bgroup\beamer@inlineframetitle{}}
\makeatother

Answer 2

To use section and subsection names in frame title in beamer, one can use \secname and \subsecname as shown below:

\section{About project}
\subsection{Easy stuff}
\begin{frame}{\secname : \subsecname}
    ...
\end{frame}