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https://github.com/aleclarson/emitter-kit

Type-safe event handling for Swift
https://github.com/aleclarson/emitter-kit

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Type-safe event handling for Swift

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README 

        

# emitter-kit v5.2.2



![stable](https://img.shields.io/badge/stability-stable-4EBA0F.svg?style=flat)

[![CocoaPods Compatible](https://img.shields.io/cocoapods/v/EmitterKit.svg?style=flat)](https://cocoapods.org/pods/EmitterKit)

[![Carthage Compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)

[![Platform](https://img.shields.io/cocoapods/p/EmitterKit.svg?style=flat)](http://cocoadocs.org/docsets/EmitterKit)



A replacement for `NSNotificationCenter#addObserver` and `NSObject#addObserver` that is **type-safe** and **not verbose**.



```swift

import EmitterKit



// A generic event emitter (but type-safe)!

var event = Event()



// Any emitted data must be the correct type.

event.emit(data)



// This listener will only be called once.

// You are *not* required to retain it.

event.once { data: T in

  print(data)

}



// This listener won't stop listening;

// unless you stop it manually,

// or its Event is deallocated.

// You *are* required to retain it.

var listener = event.on { data: T in

  print(data)

}



// Stop the listener manually.

listener.isListening = false



// Restart the listener (if it was stopped).

listener.isListening = true

```



 



### Targeting



A **target** allows you to associate a specific `AnyObject` with an `emit` call. This is useful when emitting events associated with classes you can't add properties to (like `UIView`).



When calling `emit` with a target, you must also call `on` or `once` with the same target in order to receive the emitted event.



```Swift

let myView = UIView()

let didTouch = Event()



didTouch.once(myView) { touch in

  print(touch)

}



didTouch.emit(myView, touch)

```



 



### NSNotification



The `Notifier` class helps when you are forced to use `NSNotificationCenter` (for example, if you want to know when the keyboard has appeared).



```swift

// You are **not** required to retain this after creating your listener.

var event = Notifier(UIKeyboardWillShowNotification)



// Handle NSNotifications with style!

listener = event.on { (notif: Notification) in

  print(notif.userInfo)

}

```



 



### Key-Value Observation (KVO)



```swift

// Any NSObject descendant will work.

var view = UIView()



// "Make KVO great again!" - Donald Trump

listener = view.on("bounds") { (change: Change) in

  print(change)

}

```



 



### Thread Safety



⚠️ None of the classes in EmitterKit are thread-safe!



The following actions must be done on the same thread, or you need manual locking:

- Emit an event

- Add/remove a listener

- Set the `isListening` property of a listener



 



### v5.2.2 changelog



- Fixed protocol casting (#60)



### v5.2.1 changelog



- Fix Carthage compatibility for non iOS platforms



### v5.2.0 changelog



- Added the `Event.getListeners` method

- Listeners are now always called in the order they were added

- Event.emit() can be called without an argument

- Carthage support has been improved



### v5.1.0 changelog



- The `NotificationListener` class now takes a `Notification` instead of an `NSDictionary`.



- A `NotificationListener` without a target will now receive every `Notification` with its name, regardless of the value of `notif.object`.



### v5.0.0 changelog



- Swift 3.0 + Xcode 8.0 beta 6 support



- The `Signal` class was removed. (use `Event` instead)



- The `Emitter` abstract class was removed.



- The `EmitterListener` class was renamed `EventListener`.



- The `Event` class no longer has a superclass.



- The `Notification` class was renamed `Notifier` (to prevent collision with `Foundation.Notification`).



- The `on` and `once` methods of `Event` now return an `EventListener` (instead of just a `Listener`)



- The `on` and `once` methods of `Notifier` now return an `NotificationListener` (instead of just a `Listener`)



- The `on` and `once` methods of `NSObject` now return an `ChangeListener` (instead of just a `Listener`)



- The `keyPath`, `options`, and `object` properties of `ChangeListener` are now public.



- A `listenerCount: Int` computed property was added to the `Event` class.



- An `event: Event` property was added to the `EventListener` class.



The changelog for older versions can be [found here](https://github.com/aleclarson/emitter-kit/wiki/Changelog).