How can I differentiate the background images and icon images between the different resolutions for the iPhone 5 and for the iPhone 6 and 6 Plus?
You have to turn on iOS 8 sizes in your image catalogs. They're off by default in existing projects:
来源:https://stackoverflow.com/questions/25752750/set-background-image-and-icon-image-in-iphone-6-and-6-plus