Created
November 22, 2019 13:44
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Swift's C#-like events
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| import Foundation | |
| public protocol Invocable: class { | |
| func invoke(_ notification: String, _ data: Any) | |
| } | |
| public protocol Observer: Invocable { | |
| associatedtype Value | |
| typealias Callback = (_ notification: String, _ data: Value) -> Void | |
| var callback: Callback { get } | |
| } | |
| class EventHandler<T>: Observer { | |
| typealias Value = T | |
| func invoke(_ notification: String, _ data: Any) { | |
| if let data = data as? Value { | |
| callback(notification, data) | |
| } | |
| } | |
| let callback: Callback | |
| init(callback: @escaping Callback) { | |
| self.callback = callback | |
| } | |
| } | |
| public protocol NotificationCenter { | |
| func add<T: Observer>(observer: T, for notification: String) | |
| func remove<T: Observer>(observer: T, for notification: String) | |
| func post(notification: String, data: Any) | |
| } | |
| public final class NotificationCenterImpl: NotificationCenter { | |
| typealias Storage = [String: [Invocable]] | |
| private let queue = DispatchQueue(label: "NotificationCenter") | |
| private var observers: Storage | |
| init() { | |
| observers = [:] | |
| } | |
| private var cuncurentObservers: Storage { | |
| get { | |
| var cuncurentObservers: Storage = [:] | |
| queue.async { [unowned self] in cuncurentObservers = self.observers } | |
| return cuncurentObservers | |
| } | |
| set(value) { | |
| queue.async(flags: .barrier) { | |
| self.observers = value | |
| } | |
| } | |
| } | |
| public func add<T: Observer>(observer: T, for notification: String) { | |
| var array : [Invocable] | |
| if let tempArray = cuncurentObservers[notification] { | |
| array = tempArray | |
| } else { | |
| array = [] | |
| } | |
| array.append(observer) | |
| cuncurentObservers[notification] = array | |
| } | |
| public func remove<T: Observer>(observer: T, for notification: String) { | |
| cuncurentObservers[notification]?.removeAll(where: { (item) -> Bool in item === observer }) | |
| } | |
| public func post<T>(notification: String, data: T){ | |
| cuncurentObservers[notification]?.forEach( { item in | |
| item.invoke(notification, data) | |
| }) | |
| } | |
| } | |
| let observer1 = EventHandler<String>() { print($1) } | |
| let observer2 = EventHandler<Float>() { print($1) } | |
| let notificationCenter = NotificationCenterImpl() | |
| notificationCenter.add(observer: observer1, for: "The Notification") | |
| notificationCenter.add(observer: observer2, for: "The Notification") | |
| notificationCenter.post(notification: "The Notification", data: "Stuff1") | |
| notificationCenter.post(notification: "The Notification", data: Float(0.54)) | |
| notificationCenter.remove(observer: observer1, for: "The Notification") | |
| notificationCenter.post(notification: "The Notification", data: "Stuff1") | |
| notificationCenter.post(notification: "The Notification", data: Float(0.54)) |
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