Useful iOS screen size macros

gistfile1.m

// Devices
#define ScreenHeight                    MAX([[UIScreen mainScreen] bounds].size.width,[[UIScreen mainScreen] bounds].size.height)
#define ScreenWidth                     MIN([[UIScreen mainScreen] bounds].size.width,[[UIScreen mainScreen] bounds].size.height)
#define Screen35in                      (ScreenHeight==480)
#define Screen40in                      (ScreenHeight==568)
#define Screen47in                      (ScreenHeight==667)
#define Screen55in                      (ScreenHeight==736)
#define iPad                            (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
#define iPadPro                         ((UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) && (ScreenHeight==1366))

/* USAGE */

if (Screen55in) {
    // Code specifically for iPhone 6+
}

Credit to @swaterfall for the tip about using screen height as a more reliable way to detect devices.