Beacon

A type-safe broadcasting framework to replace NSNotificationCenter

Installation

Carthage

Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks.

You can install Carthage with Homebrew using the following command:

$ brew update
$ brew install carthage

To integrate Beacon into your Xcode project using Carthage, specify it in your Cartfile:

github "zetasq/Beacon"

Run carthage update to build the framework and drag the built Beacon.framework into your Xcode project.

Usage

In Beacon, there are two kinds of roles: broadcaster and listener. Broadcasters send their signals to interested listeners.

Define a broadcaster

It's easy to make your existing class a broadcaster by conforming to SignalBroadcasting. You only need to declare two subtypes: BroadcastIdentifier and BroadcastPayload.

BroadcastIdentifier

This is like Notification.Name in the system Foundation framework. It needs to be RawRepresentable and has rawValue of type String. The easiest way is to use an enum whose rawValue is String.

You don't have to make the rawValue strings unique across your app or in other frameworks. Beacon will concatenate the bundle name, the broadcaster class name and the rawValue string to make an unique identifier.

// You have AccountManager to handle account related logic
extension AccountManager {
  
  enum BroadcastIdentifier: String, BroadcastIdentifiable {
    
    case userLogin
    
    case userLogout
  }
}

BroadcastPayload

This is like the userInfo dictionary in Notification in the system Foundation framework, but BroadcastPayload is a concrete data type. You can use any data structure(struct, class, enum...) or make a typealias to an existing subtype.

extension AccountManager {
  
  struct BroadcastPayload {
    
    let username: String
    
    let time: Date
  }
}

Don't forget add the SignalBroadcasting conformance: extension AccountManager: SignalBroadcasting {}

Broadcast signals

After you define the broadcasters, you can use them to broadcast signals.

let accountManager = AccountManager.shared

accountManager.broadcast(identifier: .userLogin, payload: .init(username: "Mr. Anderson", time: Date()))
accountManager.broadcast(identifier: .userLogout, payload: .init(username: "Mr. Smith", time: Date()))

Listen to broadcasting

As a listener, you want to listen to certain kinds of broadcasting(and maybe from a certain broadcaster!).

class InterfaceController {
  
  init() {
    Beacon.default.addListener(self, broadcasterType: AccountManager.self, broadcastIdentifier: .userLogin) { [weak self] signal in
      self?.handleUserLogin(info: signal.payload)
    }
    
    Beacon.default.addListener(self, broadcasterType: AccountManager.self, broadcastIdentifier: .userLogout) { [weak self] signal in
      self?.handleUserLogout(info: signal.payload)
    }
  }
  
  func handleUserLogin(info: AccountManager.BroadcastPayload) {
    // do something when user login
  }
  
  func handleUserLogout(info: AccountManager.BroadcastPayload) {
    // do something when user logout
  }
}

IMPORTANT: If you want to reference the listener(directly or indirectly), make sure you have added necessary weak references in the signal callback closures. Otherwise the listeners will never be released!

License

Beacon is released under the MIT license. See LICENSE for details.