How does app decide to use what Icon on ios device desktop.

I see Info.plist in project,
there is a “Icon files” property in the file.How to decide the icon

How does app decide to use what Icon on ios device desktop.
For example ,when use Icon.png? when use Icon@2x.png?
Any document talk about ios Icon setting?

<?xml version="1.0" encoding="UTF-8"?> CFBundleDevelopmentRegion English CFBundleDisplayName \${PRODUCT\_NAME} CFBundleExecutable \${EXECUTABLE\_NAME} CFBundleIconFile CFBundleIconFiles Icon.png Icon@2x.png Icon-72.png Icon-Small-50.png Icon-Small@2x.png Icon.png Icon@2x.png CFBundleIcons CFBundlePrimaryIcon CFBundleIconFiles Icon.png Icon@2x.png Icon-72.png Icon-Small-50.png Icon-Small.png Icon-Small@2x.png Icon.png Icon@2x.png UIPrerenderedIcon CFBundleIdentifier com.XXXX CFBundleInfoDictionaryVersion 6.0 CFBundleName \${PRODUCT\_NAME} CFBundlePackageType APPL CFBundleShortVersionString 1.1.1 CFBundleSignature ???? CFBundleVersion 1.1.1.1016 LSRequiresIPhoneOS UIPrerenderedIcon UIRequiredDeviceCapabilities accelerometer opengles-1 UIStatusBarHidden UISupportedInterfaceOrientations UIInterfaceOrientationPortrait