How to handle image scale on all the available iPhone resolutions?

Question

What sizes would be the best to use for images: background.png, background@2x.png and background@3x.png if we want to use this image for example to cover the full width and

Answer 1

I personally will be doing :

ImageName@2x iPhone 4/4s
ImageName-568h@2x iPhone 5/5s
ImageName-667h@2x iPhone 6
ImageName-736h@3x iPhone 6Plus

The logic behind this is that it shows a difference between all devices, whereas width shares the same value on the iPhone 5s and iPhone 4s

Edit:

This is just the naming convention I am using for resources that are device dependant, such as a background image taking the whole screen, most of the time all you want is:

ImageName@2x iPhone 4/4s/5/5s/6
ImageName@3x iPhone 6Plus/Zoom mode