IOS icon startup Screen

You don't have to worry about naming. You can directly use xcode4.3 to support visual operations. Drag it in and name it automatically. You don't need to consider the name. The icon is the same.
Application icon

Icon.png (57x57)-homescreen icon on iPhone/iPod Touch

Icon@2x.png (114x114)
-Homescreen icon on iPhone 4

Icon-72 (72X72)-homescreen
Icon on iPad

Icon-Small.png (29*29)
-Icon in spotlight and Settings app on iPhone/iPod Touch and icon in Settings app on iPad

Icon-Small-50.png (50x50)
-Icon in Spotlight on iPad

Icon-Small@2x.png (59x59)-icon in spotlight and Settings app on iPhone 4

The above icons must also be added to the icon files array of the info. plist file of the application.

Itunesartwork (512x512)-icon in iTunes for ad hoc distribution builds

Note: For iPad, an icon-72 @ 2x (144x144) is also required, which corresponds to the iPad.
3.

Start Image

IOS devices now have four different resolutions: iPhone 320x480, iPhone 4 640x960, iPad 768x1024, ipad3 1536x2048

IPhone
320x460 640x960
IPad
Portrait screen 768x1004 1536x2008
Landscape screen 1024x768 2048x1496