iOS app non-retina and retina images concept

Question

I am asking this question just for information and to clear my concepts about images in iOS application (Retina and non-retina devices

Answer 1

In ios Concept of image its also clear if you read this doc Custom Icon and Image Creation Guidelines

For Example if you want to create image

100 x 100 px so it must with 163 Resolution ppi submit.png NON-retina device

200 x 200 px so it must with 326 Resolution ppi submit@2x.png Retina device

FOR iPad:-

400 x 300 px so it must with 264 Resolution ppi submit@2x~ipad.png Retina iPad device

200 x 150 px so it must with 132 Resolution ppi submit~ipad.png Non-retina iPad device

Take a Look this Image:-

Image source from This

We inculcated @2x when we want to specify different versions of an image for iPad and iPhone. The inclusion of the @2x modifier for the high-resolution image is new and lets the system know that the image is the high-resolution variant of the standard image.

That is the key change required for the OS to size the window to fill the iPhone 5 display.has posted a writeup on this and other size-related tweaks you might need to make.

Hope this is useful info for image resolution and it's size.