How to know the device?

I am developing a comic book using Cocoa Touch in Xcode.I dont know how to get the details of the device whether the device is iphone, ipad or ipod.

I am trying for an universal build.

How to identify the device? Is there a way to change the screen size according to the device?

Solution

You can use this for you first question -

   + (BOOL)isDeviceAniPad {
    #ifdef UI_USER_INTERFACE_IDIOM
        return (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad);
    #else
        return NO;
    #endif
    }

And for you second you don't need to change it your self the iphone/ipad will use use the views sizes that fits its screen. you will have to supply different images sizes or to scale them to the size of the screen.