Is it still necessary to include non-Retina assets in iOS apps?

Question

Is it necessary to use non Retina assets in new apps?

I am asking because they take up considerable space and they're a significant time sink in my design workflow. Nowadays in late 2012, the only supported non-retina devices are steadily dying out. According to my stats: 13.8% of my users were on iPhone 3GS or older (including older iPhones and iPod Touches 3rd gen and below) during the month of September.

I'm not asking whether it's a good idea or not (sometimes it's good to create less detailed artwork for lower res devices).

I just want to know whether only including @2x assets will work reliably on non-Retina displays and whether there's any implications?

Answer 1

Not necessary. iOS will downsample the 2X resources if you don't provide a 1X version (note that the simulator's downsampling is crappy but the devices are fine).

Answer 2

Only including retina (@2x) assets works well in general on a non-retina device, but with really small assets (especially tiny icons with lots of small strokes) the results will be clearly blurry and bad. You should look at your app on a non-retina device, find assets that don't look great, and add non-retina versions for those.