Mike Swanson makes a compelling case for when to consider vector over pixel
art in your applications. With the retina iPad and the hints of high DPI
Macs, vector artwork starts making more and more sense. Keep in mind that the
iOS imaging system is optimized for the specially coded PNGs that Xcode emits
when packaging your app. If you need raw speed right at launch then you’ll want
to stick with PNG pixel art. But there will be many cases where rendering
vector images can happen asynchronously or cached off, and that’s where Mike’s
technique can be a great win.