Well, it was not that easy to install digikam on Mac. Anyway, here is the story:
I went to "Macports" to download the package to install the Macports and when Macports is installed then I type
# sudo port install digikam
to install the digikam and its dependencies (http://www.digikam.org/download?q=download/binary/).
As per instruction, it mentioned about "be prepared to wait hours for the compilation of digiKam and all its dependencies", so I was waiting and waiting for the installation to complete.
It took about an hour to complete and I was excited to open the application via Launchpad/MacPorts (Other)/digikam.app. Ooops, it throws an error:
"Run-time Qt4 SQLite or MySQL database plugin is not available - please install it.
Database plugins installed on your computer are listed below:
I googled and googled again and found a quick solution here by running:
# sudo port install qt4-mac-mysql5-plugin
The previous message didn't show up again but another message came up:
"error while opening the database.
digikam will try to automatically reconnect to the database"