To support high-resolution graphics on devices with retina displays, create two versions of each image in your app: a standard size image, and a double-sized image with "@2x" added to the name:

Standard Size:	High Resolution:
button.png 60 x 20	button@2x.png 120 x 40

To refer to an image in your code (or in Interface Builder or Storyboard), use the filename of the standard sized image. iOS will automatically detect and use the @2x version if the device supports it.

imageView.image = [UIImage imageNamed:@"button.png"];

Additional References:

• iOS Developer Library: Supporting High-Resolution Screens
• iOS Developer Library: Custom Icon and Image Creation Guidelines