[Tex/LaTex] Overlay `onslide` across slides

Question

At the moment, I have code as follows:

\documentclass{beamer}
\usetheme{Boadilla}
\usepackage[frenchb]{babel}

\begin{document}
\begin{frame}
  \frametitle{1}
\end{frame}
\begin{frame}
  \frametitle{2}
\end{frame}
\begin{frame}
  \frametitle{Overlay}
  \onslide<1->{After1\\}
  \onslide<2->{After2}
\end{frame}
\end{document}

Actually, the code doesn't realize what I want: I would like to display Overlay with After1 just after the first slide 1, and display Overlay with After1 and After2 after the slide 2.

Does anyone know how to correct the code to do so?

Answer 1

You can use \againframe:

\documentclass{beamer}
\usetheme{Boadilla}
\usepackage[frenchb]{babel}

\begin{document}
\begin{frame}
  \frametitle{1}
\end{frame}
\begin{frame}<1>[label=after]
  \onslide<1->{\frametitle{Overlay}
  After 1 }\\
  \onslide<2>{After 2}
\end{frame}
\begin{frame}
  \frametitle{2}
\end{frame}
\againframe{after}
\end{document}