Stretchable images are quite elegant: they are relatively easy to use, use less memory and memory bandwidth, perform all drawing on the GPU when paired with UII

Stretchable images are quite elegant: they are relatively easy to use, use less memory and memory bandwidth, perform all drawing on the GPU when paired with UIImageView, animate size changes effortlessly and automatically share their buffer between all image views that use a single resource. You can certainly add all of this to elements that are drawn "in code", but it's considerably more work.