IOS: image with 2x

2 sets of images should be prepared

One is for standard, format: <imagename> <device_modifier>.<Filename_extension>

One is for HD: <imagename>@2x<Device_modifier>.<Filename_extension>

Where <device_modifier> is optional, which can be "~ IPad "or "~ IPhone"

When you use the following code:

[button setImage:[UIImage imageNamed:@"play.png"] forState:UIControlStateNormal];

If retina deviceautomatically detaches an image with play@2x.png, and if yes, loads the image with @ 2x

Ref links:

Http://developer.apple.com/library/ios/#documentation/2DDrawing/Conceptual/DrawingPrintingiOS/SupportingHiResScreens/SupportingHiResScreens.html#//apple_ref/doc/uid/TP40010156-CH15-SW8

Http://stackoverflow.com/questions/3442239/retina-icons-2x-arent-being-used-when-images-are-specified-in-code

Http://stackoverflow.com/questions/9770990/uiimage-imagenamed-not-work-on-ios-5-0