A launch image looks very similar to the first screen your app displays. iOS displays this image instantly when the user starts your app and until the app is fully ready to use. As soon as your app is ready for use, your app displays its first screen, replacing the launch placeholder image.
Best way to Create Launch Images for iPhone and iPad
The best way to create launch images is by using the Simulator provided by the Xcode. Run your app inside the simulator. Let the first screen of your app be as it is. To take a screenshot, goto “File -> Save Screen Shot”. A screenshot will be saved on your desktop.
Repeat the steps with different devices to take a screenshot of each device required by the Xcode.
Edit the screenshots with your favorite image editor if any modifications are required. Be careful not to change the image size, as the Xcode will show an error if the image are not of the perfect size.
For iPad, use the iPad simulator and repeat the above steps.
iPad launch images do not include the status bar area. You can easily remove the status bar from the image using any image editing software, using the image crop functionality.
How to Add the Launch Images to Xcode
Open Xcode, goto your app target and scroll down to Launch Images. There you will see three place holder for iPhone/iPod launch images and just below it four place holders for iPad. Now Drag the files from your desktop to the xcode and place it in the appropriate Launch Image place holder.
Xcode will automatically copy the image to the project. and rename them appropriately.