Returns a list of available assertions and their system-wide levels.
- macOS 10.7+
- Mac Catalyst 13.0+
On success, this returns a CFDictionary of all assertions currently available. The keys in the dictionary are the assertion types, and the value of each is a CFNumber that represents the aggregate level for that assertion. Caller must CFRelease() this dictionary when done.
Returns kIOReturnSuccess on success.
The system-wide level is the maximum of all individual assertions' levels.