app icon

Table 41-1Size (in pixels) of custom icons and images

Asset

iPhone 6 Plus (@3x)

iPhone 6 and iPhone 5 (@2x)

iPhone 4s (@2x)

iPad and iPad mini (@2x)

iPad 2 and iPad mini (@1x)

App icon (required for all apps)	180 x 180	120 x 120	120 x 120	152 x 152	76 x 76
App icon for the App Store (required for all apps)	1024 x 1024	1024 x 1024	1024 x 1024	1024 x 1024	1024 x 1024
Launch file or image (required for all apps)	Use a launch file (see Launch Images)	For iPhone 6, use a launch file (see Launch Images) For iPhone 5, 640 x 1136	640 x 960	1536 x 2048 (portrait) 2048 x 1536 (landscape)	768 x 1024 (portrait) 1024 x 768 (landscape)
Spotlight search results icon (recommended)	120 x 120	80 x 80	80 x 80	80 x 80	40 x 40
Settings icon (recommended)	87 x 87	58 x 58	58 x 58	58 x 58	29 x 29
Toolbar and navigation bar icon (optional)	About 66 x 66	About 44 x 44	About 44 x 44	About 44 x 44	About 22 x 22
Tab bar icon (optional)	About 75 x 75 (maximum: 144 x 96)	About 50 x 50 (maximum: 96 x 64)	About 50 x 50 (maximum: 96 x 64)	About 50 x 50 (maximum: 96 x 64)	About 25 x 25 (maximum: 48 x 32)
Default Newsstand cover icon for the App Store (required for Newsstand apps)	At least 1024 pixels on the longest edge	At least 1024 pixels on the longest edge	At least 1024 pixels on the longest edge	At least 1024 pixels on the longest edge	At least 512 pixels on the longest edge
Web clip icon (recommended for web apps and websites)	180 x 180	120 x 120	120 x 120	152 x 152	76 x 76

参考链接：苹果官网