Registers a listener that fires when system power events occur.
"screensDidSleep", "screensDidWake", "screensDidLock", "screensDidUnlock",
"screensaverDidStart", "screensaverDidStop", "screensaverWillStop",
"systemWillSleep", "systemDidWake", "systemWillPowerOff",
"sessionDidBecomeActive", "sessionDidResignActive".
The OS notification subscription starts lazily on the first listener and
is released automatically when the last listener is removed.
Parameters
listener: (eventName:string)=>void
A function called with the power event name string.
Registers a listener that fires when system power events occur.
"screensDidSleep","screensDidWake","screensDidLock","screensDidUnlock","screensaverDidStart","screensaverDidStop","screensaverWillStop","systemWillSleep","systemDidWake","systemWillPowerOff","sessionDidBecomeActive","sessionDidResignActive". The OS notification subscription starts lazily on the first listener and is released automatically when the last listener is removed.