- what is the archetype used?
A swing application is a standard JAR so just use the standard archetype:
mvn archetype:generate -DgroupId=com.mycompany.app \
-DartifactId=myswingapp \
-Dversion=1.0-SNAPSHOT
- what are the dependencies?
If you plan to use the standard Swing API only, there aren't no extra dependencies to declare. But if you want to use things like JGoodies, MiGLayout, SwingX, Flamingo, SwingFX etc then you'll have to add the appropriate artifacts and repositories. But there is no universal answer to your question.
- how to build swing app in maven [is there is plugin to do so ]?
A Swing app is not really particular. I would maybe just consider using Java Web Start (and the Maven Webstart plugin) or maybe a cross platform installer like IzPack (and the Maven IzPack Plugin). But you have time for that, you need an application before :)