generate Class diagram for iphone app
Just download OmniGraffle and then go to File->Open->Select your XcodeProject file
and that's it you'll have a class diagram.
Select the "FirstDemo.xcdatamodeld".Goto the "File" select the "print" option save as pdf formate in "ERD diagram".
Any screen issue faced goto the "File" select the "Page Setup"manage the custom sizes.