Initial Commit

Sources/WittyMessageCenter/WittyMessageCenter.swift

@@ -1,3 +1,100 @@
-struct WittyMessageCenter {
-    var text = "Hello, World!"
+//
+//  MessageCenter.swift
+//  PSArsenal
+//
+//  Created by Prajeet Shrestha on 01/06/2021.
+//
+
+import Foundation
+///
+///A class to simplify usage of NSNotificationCenter
+///
+/// **Example:**
+///
+/// **1. Initialize**
+///
+///     let messageCenter = MessageCenter()
+///
+/// **2.0 Send Notification**
+///
+///     //2.1. Send Notification without data
+///     messageCenter.send(name: .homePageFetchComplete)
+///
+///     //2.2 Send Notification with data
+///     messageCenter.send(name: .homePageFetchComplete, ["name": "Prajeet"])
+///
+/// **3.0 Observe Notification**
+///
+///     //3.1 Observe without data
+///     messageCenter.observe(name: .homePageFetchComplete) {[weak self] _ in
+///         self?.lblMessage.text = "Got Notification"
+///     }
+///
+///     //3.2 Observe with data
+///     messageCenter.observe(name: .homePageFetchComplete) {[weak self] data in
+///     self?.lblMessage.text = "Got Notification"
+///
+/// **Notes**
+///
+/// 1. Can cause cyclic reference.
+/// 2. There will be a retention cycle, if callback methods capture strong references and you don't call remove() method.
+/// 3. You can use weak reference in callback closures to prevent retention cycle.
+/// 4. If you use weak references then you don't need to call remove() method explicitly.
+
+public class MessageCenter {
+    private static let notificationCenter = NotificationCenter()
+    public var scope:String = ""
+    public typealias CallBack = (_ data:[AnyHashable:Any]?) -> Void
+
+    public init() {}
+
+    private var callbackStore = [String : CallBack]()
+
+    /// Observe Notification in NSNotificationCenter.default
+    /// - Parameters:
+    ///   - name: Name of a notification as string
+    ///   - callback: Closure to be executed upon receiving notificaitons
+    ///
+    ///callback will also return a userinfo as data from dictionary
+
+    public func observe(name:String, callback:@escaping CallBack) {
+
+        MessageCenter.notificationCenter.addObserver (self,
+                                                      selector: #selector(self.notificationCallback),
+                                                      name: NSNotification.Name(name),
+                                                      object: nil)
+        callbackStore[name] = callback
+    }
+
+
+    /// Sends notification through NSNotificationCenter.default
+    /// - Parameters:
+    ///   - name: Name of notification as string
+    ///   - data: Data to be passed as user info in Notification Object
+    public func send(name:String, data:[String:AnyObject]? = nil) {
+        MessageCenter.notificationCenter.post(name: NSNotification.Name(name),
+                                              object: nil, userInfo:data)
+    }
+
+    /// Method to remove notification observer
+    public func remove() {
+        callbackStore.removeAll()
+        MessageCenter.notificationCenter.removeObserver(self)
+    }
+
+    @objc private func notificationCallback(notification: Notification) {
+        if let callback = callbackStore[notification.name.rawValue] {
+            callback(notification.userInfo)
+        }
+    }
+
+    deinit {
+        //print("MessageCenter deinit from: \(scope)")
+        remove()
+    }
+}
+
+public protocol Notifiable {
+    var messageCenter:MessageCenter { get }
+    func observeNotifications()
 }