i had just looked this up yesterday. I haven't tried it yet but here are the links i found that answered it: http://docs.appcelerator.com/titanium/latest/#!/guide/Icons_and_Splash_Screens-section-29004897_IconsandSplashScreens-iOSgraphicassetrequirementsandoptions
if you have language specific: http://docs.appcelerator.com/titanium/latest/#!/guide/Icons_and_Splash_Screens-section-29004897_IconsandSplashScreens-iOS