IPhone5 and iPhone6 @ 2x Image Issue
What is the official iOS naming convention for (@ 2X),
iPhone 6:
667x375 pixels 1334x750 pixels 2x scale 1334x750 physical pixels 326 physical ppi 4.7 "
iPhone 5:
568x320 pixels 1136x640 pixels 2x scale 1136x640 physical pixels 326 physical ppi 4.0 "
iPhone 4:
480x320 pixels 960x640 pixels 2x scale 960x640 physical pixels 326 physical ppi 3.5 "
So this device recognizes an image (with @ 2X) for an iPhone 6, iPhone 5, or iPhone 4?
There is no publicly available way to differentiate your images between different device subtypes. If you have to download a separate image depending on whether your app is running on an iPhone 4, 5 or 6, you will need to perform device detection and load the whole image into your own code (use differentiate screen size).
You can try @ 3x , although I haven't tested it.