iOS spotlight icon won't show

For my app icon I have crossed Iphone: iOS 8 and later and iOS 7 and later and ipad: iOS 7 and later then I transferred all 12 icons but when I do a spotlight search in my iphone the icon won't show up. Have I missed something?

Also, what does iOS icon is pre-renered option mean and do I need it?

Thanks

via Chebli Mohamed