What event is fired when Mac is back from sleep?

Question

I am developing an app in Xcode on Mac and would like to know the event which is fired when the mac gets back from sleep. AwakeFromNib doesn't seem to work.

Answer 1

For swift 3:

func onWakeNote(note: NSNotification) {
    print("Received wake note: \(note.name)")
}

func onSleepNote(note: NSNotification) {
    print("Received sleep note: \(note.name)")
}

func fileNotifications() {
    NSWorkspace.shared().notificationCenter.addObserver(
        self, selector: #selector(onWakeNote(note:)),
        name: Notification.Name.NSWorkspaceDidWake, object: nil)

    NSWorkspace.shared().notificationCenter.addObserver(
        self, selector: #selector(onSleepNote(note:)),
        name: Notification.Name.NSWorkspaceWillSleep, object: nil)
}

For swift 4:

@objc func onWakeNote(note: NSNotification) {
    ...
}

@objc func onSleepNote(note: NSNotification) {
    ...
}

func fileNotifications() {
    NSWorkspace.shared.notificationCenter.addObserver(
        self, selector: #selector(onWakeNote(note:)),
        name: NSWorkspace.didWakeNotification, object: nil)

    NSWorkspace.shared.notificationCenter.addObserver(
        self, selector: #selector(onSleepNote(note:)),
        name: NSWorkspace.willSleepNotification, object: nil)
}

Answer 2

You can use IORegisterForSystemPower().

Connects the caller to the Root Power Domain IOService for the purpose of receiving sleep & wake notifications for the system. Does not provide system shutdown and restart notifications.

io_connect_t IORegisterForSystemPower (
    void *refcon, 
    IONotificationPortRef *thePortRef, 
    IOServiceInterestCallback callback, 
    io_object_t *notifier ) ;  

Take a look at Q:How can my application get notified when the computer is going to sleep or waking from sleep? How to I prevent sleep?