Which resolution of images to use for watch kit?

Question

Images.xcassets in watchkit has options for 1x, 2x and 3x.

But how do we know which one to use ? Both are retina, but have different screen sizes. Do we have to supply all three? What happens if you don't ?

EDIT: I have tried putting the image in 1x and 2x, and haven't noticed any difference so far, but that could just be an absence of my testing. Nothing else.

Answer 1

They are all @2x. You can configure your xcassets image set to actually be specific for the Apple Watch by specifying the device. Below is a screenshot demonstrating how to do this.

Hopefully that helps clarify things.

Answer 2

It'll use the closest available match. But the Watch is retina native so ideally you would provide just @2x; bundling more will just take up unneeded space.