Use Quick Look to inspect images in the Xcode debugger.
Select an NSImage or UIImage in the debugger, then click the Quick Look “eye” icon.
Like other areas of OS X, you can also use spacebar to Quick Look!
Quick Look in the debugger can also be implemented for your own classes:
Enabling Quick Look for Custom Types
The variables Quick Look feature in the Xcode debugger allows you to obtain a quick visual assessment of the state of an object variable through a graphical rendering, displayed in a popover window either in the debugger variables view or in place in your source code.
This chapter describes how you implement a Quick Look method for your custom class types so that object variables of those types can also be rendered visually in the Quick Look popover window.