As far as I can tell Photoshop Documents don’t have Swatches, the Application does.
Sorry for my ignorance..
I had looked into it but I didn't find anything useful in their, related to my task..
Although It seems like there, we can get the list of swatches name and from the name we can get the color values. And after that I can match the values with the fill color of selected art object.
What I am looking here something like, set the rgb values in the keys and by using action manager code I can get the swatch name.