The number of bits of numeric precision available for each feature channel.
Mac Catalyst 13.0+Beta
Metal Performance Shaders
This is precision, not size (float is 24 bits, not 32; half-precision floating-point is 11 bits, not 16; Snorm pixel formats have one less bit of precision for the sign bit, etc.). For formats like MTLPixelFormatB5G6R5Unorm, this value is the precision of the most precise channel (which is 6 in this case). When this information is unavailable, typically for compressed formats, this value is 0.
This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.