I'm going to make IOS app, and i will get interface mockups of my app from designer. But i don't know in which format he will send me interface whether in PSD format or JPEG format.

with the given format i want to find all specs like X coordinates, Y coordinates, width, height and distance between each element present in the interface in points or pixels.

So, is there any tool to get all the specs..?? I have searched for the similar tools and i found one tool xScope(http://xscopeapp.com/) but i have not used it yet. Plz give me some suggestion about this tool(effective or not) or any other tools(any free tools exist).