Swift 4.0 & Xcode 9.0+:

Send(Post) Notification:

NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: nil)

OR

NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: nil, userInfo: ["Renish":"Dadhaniya"])

Receive(Get) Notification:

NotificationCenter.default.addObserver(self, selector: #selector(self.methodOfReceivedNotification(notification:)), name: Notification.Name("NotificationIdentifier"), object: nil)

Function-Method handler for received Notification:

@objc func methodOfReceivedNotification(notification: Notification) {}

Swift 3.0 & Xcode 8.0+:

Send(Post) Notification:

NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: nil)

Receive(Get) Notification:

NotificationCenter.default.addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification(notification:)), name: Notification.Name("NotificationIdentifier"), object: nil)

Method handler for received Notification:

func methodOfReceivedNotification(notification: Notification) {  // Take Action on Notification}

Remove Notification:

deinit {  NotificationCenter.default.removeObserver(self, name: Notification.Name("NotificationIdentifier"), object: nil)}

Swift 2.3 & Xcode 7:

Send(Post) Notification

NSNotificationCenter.defaultCenter().postNotificationName("NotificationIdentifier", object: nil)

Receive(Get) Notification

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification(_:)), name:"NotificationIdentifier", object: nil)

Method handler for received Notification

func methodOfReceivedNotification(notification: NSNotification){  // Take Action on Notification}

For historic Xcode versions...

Send(Post) Notification

NSNotificationCenter.defaultCenter().postNotificationName("NotificationIdentifier", object: nil)

Receive(Get) Notification

NSNotificationCenter.defaultCenter().addObserver(self, selector: "methodOfReceivedNotification:", name:"NotificationIdentifier", object: nil)

Remove Notification

NSNotificationCenter.defaultCenter().removeObserver(self, name: "NotificationIdentifier", object: nil)NSNotificationCenter.defaultCenter().removeObserver(self) // Remove from all notifications being observed

Method handler for received Notification

func methodOfReceivedNotification(notification: NSNotification) {  // Take Action on Notification}

Annotate either the class or the target method with @objc

@objc private func methodOfReceivedNotification(notification: NSNotification) {  // Take Action on Notification}// Ordynamic private func methodOfReceivedNotification(notification: NSNotification) {  // Take Action on Notification}

It's the same as the Objective-C API, but uses Swift's syntax.

Swift 4.2 & Swift 5:

NotificationCenter.default.addObserver(    self,    selector: #selector(self.batteryLevelChanged),    name: UIDevice.batteryLevelDidChangeNotification,    object: nil)

If your observer does not inherit from an Objective-C object, you must prefix your method with @objc in order to use it as a selector.

@objc private func batteryLevelChanged(notification: NSNotification){         //do stuff using the userInfo property of the notification object}

See NSNotificationCenter Class Reference, Interacting with Objective-C APIs

A nice way of doing this is to use the addObserver(forName:object:queue:using:) method rather than the addObserver(_:selector:name:object:) method that is often used from Objective-C code. The advantage of the first variant is that you don't have to use the @objc attribute on your method:

    func batteryLevelChanged(notification: Notification) {        // do something useful with this information    }    let observer = NotificationCenter.default.addObserver(        forName: NSNotification.Name.UIDeviceBatteryLevelDidChange,        object: nil, queue: nil,        using: batteryLevelChanged)

and you can even just use a closure instead of a method if you want:

    let observer = NotificationCenter.default.addObserver(        forName: NSNotification.Name.UIDeviceBatteryLevelDidChange,        object: nil, queue: nil) { _ in print("🔋") }

You can use the returned value to stop listening for the notification later:

    NotificationCenter.default.removeObserver(observer)

There used to be another advantage in using this method, which was that it doesn't require you to use selector strings which couldn't be statically checked by the compiler and so were fragile to breaking if the method is renamed, but Swift 2.2 and later include #selector expressions that fix that problem.