added flyweight pattern

Author: Sebastian Boldt

GOFSwift.xcworkspace/contents.xcworkspacedata

@@ -33,7 +33,7 @@
 * ✅ Decorator
 * ✅ Composite
 * ✅ Adapter
+* ✅ Flyweight
 * ❌ Facade
-* ❌ Flyweight
 * ❌ Protection Proxy
 * ❌ Virtual Proxy

README.md

@@ -0,0 +1,75 @@
+//: [Previous](@previous)
+
+import Foundation
+
+protocol Soldier {
+    func render(from location: CGPoint, to newLocation: CGPoint)
+}
+
+class Infantry: Soldier {
+    private let modelData: Data
+    
+    init(modelData: Data) {
+        self.modelData = modelData
+    }
+    
+    func render(from location: CGPoint, to newLocation: CGPoint) {
+        // Remove rendering from original location
+        // Graphically render at new location
+    }
+}
+
+class SoldierClient {
+    var currentLocation: CGPoint
+    
+    let soldier: Soldier
+    
+    init(currentLocation: CGPoint, soldier: Soldier) {
+        self.currentLocation = currentLocation
+        self.soldier = soldier
+    }
+    
+    func moveSoldier(to nextLocation: CGPoint) {
+        soldier.render(from: currentLocation, to: nextLocation)
+        currentLocation = nextLocation
+    }
+}
+
+class SoldierFactory {
+    
+    enum SoldierType {
+        case infantry
+    }
+
+    private var availableSoldiers =  [SoldierType: Soldier]()
+    static let sharedInstance = SoldierFactory()
+    
+    private init(){}
+    
+    private func createSoldier(of type: SoldierType) -> Soldier {
+        switch type {
+        case .infantry:
+            let infantry = Infantry(modelData: Data())
+            availableSoldiers[type] = infantry
+            return infantry
+        }
+    }
+    
+    func getSoldier(type: SoldierType) -> Soldier {
+        if let soldier = availableSoldiers[type] {
+            return soldier
+        } else {
+            let soldier = createSoldier(of: type)
+            return soldier
+        }
+    }
+}
+
+let soldierFactory = SoldierFactory.sharedInstance
+let infantry = soldierFactory.getSoldier(type: .infantry)
+let firstSoldier = SoldierClient(currentLocation: CGPoint.zero, soldier: infantry)
+let secondSoldier = SoldierClient(currentLocation: CGPoint(x: 5, y: 10), soldier: infantry)
+
+firstSoldier.moveSoldier(to: CGPoint(x: 1, y: 5))
+
+//: [Next](@next)

Structural.playground/Pages/Flyweight.xcplaygroundpage/Contents.swift

@@ -5,5 +5,6 @@
         <page name='Decorator'/>
         <page name='Composite'/>
         <page name='Adapter'/>
+        <page name='Flyweight'/>
     </pages>
 </playground>