Apple new announcement

Question

Please help I am an iOS developer and just have announced about Apple's new motivation about retina displays. When you create or update your apps in iTunes Connect, you must upload screenshots that are high-resolution. We require your screenshots as high-resolution images so that your app is optimized for the Retina display.

I am not quite understand what it will change in the way that I develop application in Xcode. For example if the designer in the past provided me with image in 20x30 sizes, should she now provide me the same image with other size? Also I know that iPhone's display is 320X480 . How this new approach of Apple will effect on this?

Answer 1

The new requirement is that "screenshots" submitted to the iTunes store (not in the app) be at Retina size, that means 640 x 960 pixels for a full display image.

Note: A non-retina iPhone display is 320 x 480 pixels, a retina iPhone display is 640 x 960 pixels.

Answer 2

for retina you need double sized images. if you had an image sized 20x20 in the past, for retina you need to have 40x40 pixels. like:

non retina: myImage.png  
retina:     myImage@2x.png

iOS will take care of the rest. you should only refer to myImage.png in your app.

Answer 3

If you're developing for non-retina iphones then a 20x30px image will display fine, however that same image on an iPhone4/4s will appear blurred as there are twice as many pixels as before. Your designer will need to make new images in high definition so 40x60 for the iPhone, and you can add them to your project with the prefix image_name@2x.png. The application will decide which image to use. Do not scale the image, as it won't work.

https://developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/MobileHIG/IconsImages/IconsImages.html#//apple_ref/doc/uid/TP40006556-CH14-SW2