I'm creating a universal device app game. For iPhone 4s,5,5c,5s,6,6+ and iPad Retina's and non-retina's that support iOS 6.1+. I have about 40 images for the game different sizes. In Images.xcassets when I create a New Image Set, how do I place all iPhone 1x and iPad 1x non-retina and iPhone2x and iPad 2x Retina images for the Universal 1x, 2x, 3x with only 3 spaces?