main.lua

-- handle special cases like iPad retina
DPI_SCALE = 1

if Util.isIPadRetina () then

    print ( "Why, iPad Retina; what big pixels you have." )

    DPI_SCALE = 2

    DISPLAY_WIDTH = 1024
    DISPLAY_HEIGHT = 768

end

-- game window should be 1024
MOAISim.openWindow( GAME_NAME , DISPLAY_WIDTH, DISPLAY_HEIGHT )

-- while viewport should be @2x at 2048
VIEWPORT = MOAIViewport.new ()
VIEWPORT:setSize ( DISPLAY_WIDTH * DPI_SCALE, DISPLAY_HEIGHT * DPI_SCALE )
VIEWPORT:setScale ( GAME_SCREEN_X, -GAME_SCREEN_Y )
VIEWPORT:setOffset ( -1, 1 )

util.lua

function Util.isIPadRetina ()

    if MOAIEnvironment.osBrand == Util.OS_BRAND_IOS then

        if DISPLAY_WIDTH >= 2048 then

            return true

        end

    end

    return false

end