iOS 7 App Icons, Launch images And Naming Convention While Keeping iOS 6 Icons

Absolutely Asset Catalog is you answer, it removes the need to follow naming conventions when you are adding or updating your app icons.

Below are the steps to Migrating an App Icon Set or Launch Image Set From Apple:

1- In the project navigator, select your target.

2- Select the General pane, and scroll to the App Icons section.

3- Specify an image in the App Icon table by clicking the folder icon on the right side of the image row and selecting the image file in the dialog that appears.

4-Migrate the images in the App Icon table to an asset catalog by clicking the Use Asset Catalog button, selecting an asset catalog from the popup menu, and clicking the Migrate button.

Alternatively, you can create an empty app icon set by choosing Editor > New App Icon, and add images to the set by dragging them from the Finder or by choosing Editor > Import.

You should use Asset Catalog:

I have investigated, how we can use Asset Catalog; Now it seems to be easy for me. I want to show you steps to add icons and splash in asset catalog.

Note: No need to make any entry in info.plist file :) And no any other configuration.

In below image, at right side, you will see highlighted area, where you can mention which icons you need. In case of mine, i have selected first four checkboxes; As its for my app requirements. You can select choices according to your requirements.

Now, see below image. As you will select any App icon then you will see its detail at right side selected area. It will help you to upload correct resolution icon.

If Correct resolution image will not be added then following warning will come. Just upload the image with correct resolution.

After uploading all required dimensions, you shouldn't get any warning.

In case you do not want to use Asset Catalog, you can add an iOS 7 icon for an old app by creating a 120x120 .png image. Name it Icon-120.png and drag in to the project.

Under TARGET > Your App > Info > Icon files, add one more entry in the Target Properties:

I tested on Xcode 5 and an app was submitted without the missing retina icon warning.