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

With the given format i want to find all specs like X-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 and found [xScope](http://xscopeapp.com/) but i have not used it yet. Is this tool effective or not? Are there any other free tools?