TEPopUp uses resizableImageWithCapInsets
TEPopUp show a pop-up view that stands on a translucent view, it can add something in the dialog view easily.
TEPopUp dialog use the api, UIImage resizableImageWithCapInsets:, it needs not a full size picture as its background picture, instead of a 28x28 pixel small picture. Obviously, this technical can reduce the who app size. The main core code cuts the area of pattern image, from the center point to right-bottom corner by UIEdgeInsetsMake. Then, the UIImage returns a new instance thats already expand image to appropriate size.