I want to make my App compatible for iPhone 5, i got the point about auto resizing just need to confir, Do i need to add all the images re-sized for iPhone 5 OR can work with re-sizeing only Splash and Background image ?
You will be required to resize the launch images. You need a launch image for the older iPhone screen sizes in normal and retina resolutions as well as an iPhone 5 screen size retina image.
It will be a good idea to rework your app and have background images that can take advantage of the larger iPhone 5 screen size, but will be able to be cropped and still work on the older iPhone screens.
Using either auto layout or setting the resize and pinning struts properly, your other controls and images should be able to be used as they are to adapt your app to look good on the iPhone 5 screen.