can the ui design for old iphone be used on iphone4?

I'm developing my softwa开发者_运维问答re, all the ui is drawn based on 480x320 size screen, can my software run on iphone4 without any modification?

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Yes it can run with no modification.

If you'd like to create "retina" assets you can create all of your images at the double resolution and include copies with '@2x' appended to the filename in your Application bundle. The iPhone will automatically load the correct images.

Example: existing image - myImage.png new up-sampled image - myImage@2x.png

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Yes, but any images sized for the earlier iPhone models will look chunky compared to custom-designed iPhone 4 images.

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Both the iPhone 4 and older devices are 320x480 points in size, which is the coordinate system that Core Graphics and UIKit uses. So your software will run the same.

Only the automatic scaling between your bitmaps and the display will be different. If you have bitmapped content or images, you can optionally provide @2x sized versions that will look somewhat smoother without the 2X scaling on iPhone 4 devices. This is nice, but optional.