In xcode 7 these is no retina 4 option, according to this, apple removed it on purpose. I did edit Contents.json to get it back but the effect is not the same! I remember in XCode6/pre-iOS9 iPhone 6 will used retina 4 picture so I only need to set one fullscreen 2x picture for iPhone 4/4s, one fullscreen Retina 4 for iPhone 5/5s and 6.
I think using Retina4 for iPhone 6 really makes sense while 2x doesn't! Because 1334/750 is about 1.778, which is close to 1136/640 = 1.775 while 960/640 = 1.5. My 640*1136 pictures do show properly on iPhone 6 while 640*960 pictures are distorted.
But with Xcode 7 even I got the retina 4 option back, iPhone 6 still use 2x (640*960) picture instead of retina4 picture(iPhone 5/5s does use retina4 and shows properly now). I tried to change device type from iPhone to Universal, same.
So my question is if apple removed retina4 on purpose then how do I set fullscreen images in xasset to make them work for iPhone 4/5/6 ? I am only talking about fullscreen images. I understand for non-fullscreen images using 2x makes sense.
BTW I am not talking about AppIcon & LaunchImage (retina 4 is still there and works). I don't want to write extra code to make it work (actually this is what I currently do, like this Fullscreen images on iPhone 6 with Asset Catalogs) either. So is it possible that I just set asset to make it work ?