I have a GTk TreeView called MyTree with the following data as presented below,
DTime ATime Transfer Platform
14:30 15:20 0 2a
Since you are in BROWSE selection mode, you know there is only one selected row. Then, you can get the path to the first selected item doing
path = iter.get_selected_rows()[0]
Then, if your tree has only one level (e.g. it is not a nested tree), you can get the index from the path like this
index = path.get_indices()[0]
It seems complicated, but this is because you selection could contains many rows (this is why it returns a list) and because the tree can have many levels (this is why it returns a path).