Returns the estimated minutes remaining until all power sources (battery and/or UPS's) are empty, or returns
k if attached to an unlimited power source.
- macOS 10.7+
If attached to an "Unlimited" power source, like AC power or any external source, the return value is
If the system is on "Limited" power, like a battery or UPS, but is still calculating the time remaining, which may take several seconds after each system power event (e.g. waking from sleep, or unplugging AC Power), the return value is
Otherwise, if the system is on "Limited" power and the system has an accurate time remaining estimate, the system returns a CFTimeInterval estimate of the time remaining until the system is out of battery power.