[Add] Observer 패턴 추가 #10

SOPTving/SOPTving/Utility/DesignPattern/Observable.swift

@@ -0,0 +1,42 @@
+//
+//  Observable.swift
+//  SOPTving
+//
+//  Created by 장석우 on 2023/04/28.
+//
+
+import Foundation
+
+final class Observable<T> {
+
+    struct Observer<T> {
+        weak var observer: AnyObject?
+        let block: (T) -> Void
+    }
+
+    private var observers = [Observer<T>]()
+
+    var value: T {
+        didSet { notifyObservers() }
+    }
+
+    init(_ value: T) {
+        self.value = value
+    }
+
+    func observe(on observer: AnyObject, observerBlock: @escaping (T) -> Void) {
+        observers.append(Observer(observer: observer, block: observerBlock))
+        observerBlock(self.value)
+    }
+
+    func remove(observer: AnyObject) {
+        observers = observers.filter { $0.observer !== observer }
+    }
+
+    private func notifyObservers() {
+        for observer in observers {
+            observer.block(self.value)
+        }
+    }
+}
+