For start what I am trying to do i am not even sure that is possible(looks that is) In the feature of image assets in Xcode you can select for an imageSet to be either Universal or Device Specific. When I am doing it Device Specific and select both iphone and Retina 4 and assign pics to all , it is always selected the iphone retina image and never the Retina 4 when I am using an iphone 5(device or simulator)
Have searched docs but couldnt find something. Thanks
The "R4" image will only work on 4-inch iPhone running iOS 7 or later. On older version of iOS it will use 2x image.
Example. If you use images like this:
you will see:
- iPhone 5 iOS >= 7 - number 3,
- iPhone 5 iOS < 7 - number 2,
- iPhone 4, 4S - number 2,
- iPhone 3GS - number 1,
- iPhone 5C and 5S - number 3.
In my experience, this is the case whenever you do not target specifically iOS 7.0 in your Deployment Target as part of your Project/Workspace settings.
Targeting anything other than 7.0 seems to result in this behavior.
To clarify: this value essentially specifies the minimum version of iOS that is allowed to run your app. Specifying iOS 7.0 in this field will restrict use of your app/update to ONLY users with iOS 7.0.
来源：https://stackoverflow.com/questions/18744554/image-assets-catalog-doesnt-recognise-retina-4-photos-in-xcode5