What should the size of the MPMediaItemPropertyArtwork in MPNowPlayingInfoCenter be?

Question

I want to set the image in iOS lock screen but the documentation never mentions the size of the artwork. What should it be set to?

Answer 1

On the apple forums people recommend 600x600 images or higher,

I found any lower than that looks blurry.

https://discussions.apple.com/thread/6521841?start=0&tstart=0