Implemented Iterator Pattern

Author: Sebastian Boldt

Behavioral.playground/Pages/Iterator.xcplaygroundpage/Contents.swift

@@ -0,0 +1,41 @@
+//: [Previous](@previous)
+
+import Foundation
+
+public struct Book {
+    var name : String
+}
+
+public struct Library {
+    var catalog = [Book]()
+}
+
+public struct LibraryIterator : IteratorProtocol {
+    
+    public  var lib : Library
+    private var currentIndex : Int = 0
+    
+    public init(lib: Library) {
+        self.lib = lib
+    }
+    
+    mutating public func next() -> Book? {
+        defer{ currentIndex = currentIndex + 1}
+        return currentIndex >= lib.catalog.count ? nil : lib.catalog[currentIndex]
+    }
+}
+
+extension Library : Sequence {
+    public func makeIterator() -> LibraryIterator {
+        return LibraryIterator(lib:self)
+    }
+}
+
+
+let catalog = [Book(name:"Bla"),Book(name:"Blub"),Book(name:"Foo")]
+let library = Library(catalog: catalog)
+
+for book in library {
+    print(book.name)
+}
+//: [Next](@next)

Behavioral.playground/contents.xcplayground

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<playground version='6.0' target-platform='ios' display-mode='raw'>
+<playground version='6.0' target-platform='ios' display-mode='raw' executeOnSourceChanges='false'>
     <pages>
-        <page name='Intro'/>
         <page name='Chain of Responsibility '/>
         <page name='Command'/>
+        <page name='Iterator'/>
     </pages>
 </playground>

GOFSwift.xcworkspace/xcuserdata/sebastianboldt.xcuserdatad/UserInterfaceState.xcuserstate

@@ -11,13 +11,13 @@ Inspired by: https://github.com/ochococo/Design-Patterns-In-Swift
 
 * ✅ Chain Of Responsibility 
 * ✅ Command
+* ✅ Iterator
+* ❌ Strategy
 * ❌ Interpreter
-* ❌ Iterator
 * ❌ Mediator
 * ❌ Memento
 * ❌ Observer
 * ❌ State
-* ❌ Strategy
 * ❌ Visitor
 
 ##Creational