The following list and table show specifications and requirements for iOS screenshots for 3.5-inch Retina displays:
File Type: High-quality JPEG, TIFF, or PNG
Quality: 72 dpi, RGB, flattened
Transparency: Not allowed
Required: At least one
Type
Dimensions (px)
Notes
Portrait
640 x 920
Hi-res, do not include status bar
Portrait
640 x 960
Hi-res, fullscreen
Landscape
960 x 600
Hi-res, do not include status bar
Landscape
960 x 640
Hi-res, fullscreen