I am a little confused about how retina images work in Xcode. I understand that if I use the image assets I can specify the 2* and 3* images for retina and iPhone6+ respectively and I just reference the image and Xcode does the rest. What about if I am using an image that isn't from the assets though? Say for example I am storing images of a users profile picture on the server, if I had a 70*70pt profile picture would I just set the image as a 140*140px one for the retina display? For the 6+ would I do the same? Set a 210*210 one?