Apple's "human interface guidelines" is clear about which side (left or right) you should place certain tool-bar buttons: CANCEL (left).... and.... DONE (right).
Which side (left or right) should other buttons go on?
ADD and DONE EDIT and SAVE EDIT and ADD SORT and SEARCH SORT DIRECTION and SORT FIELD CANCEL ADD
This is by no means an answer, just an opinion.. i wouldve commented it but for some reason it wont let me..
From what ive gathered, any thing that take you to a previous state: i.e cancel, back, etc would be on the left side..
anything that take you to a forward state, i.e save, add, done, etc would be on the right side.. now depending on the view, whether a button belongs on the left or right might vary..
for example:
consider a ui table view that contains data.. at the top of this view i dont thing id have anything on the top LEFT (unless this table view is NOT the primary view, in which case i probably would have some sort of back button) on the top RIGHT i would probably have and edit button that lets me delete something from this table view
upon selecting a specific line i would be directed to another view specific to that piece of data.. at the top LEFT i would have a back button and on the top RIGHT i may have another button with more specific functions that were not available on the previous tableview..
this is by no means an answer just an idea to maybe help clarify your situation.. if you look at the hierarchy of your application, you'l often determine the bast place to provide a certain function and whether it actually belongs there
hope it helps
