added Dependency Inversion playground and updated README.md

README.md

@@ -9,41 +9,64 @@
 
 ### Behavioral
 
-* ✅ Chain Of Responsibility 
-* ✅ Command
-* ✅ Iterator
-* ✅ Strategy
-* ✅ Mediator
-* ✅ Visitor
-* ✅ Observer
-* ✅ Memento
-* ✅ State
-* ❌ Interpreter
+✅ Chain Of Responsibility
+
+✅ Command
+
+✅ Iterator
+
+✅ Strategy
+
+✅ Mediator
+
+✅ Visitor
+
+✅ Observer
+
+✅ Memento
+
+✅ State
+
+❌ Interpreter
 
 ### Creational
 
-* ✅ Singleton
-* ✅ Prototype
-* ✅ Factory Method
-* ✅ Builder 
-* ✅ Abstract Factory
+✅ Singleton
+
+✅ Prototype
+
+✅ Factory Method
+
+✅ Builder
 
+✅ Abstract Factory
 
 ### Structural
 
-* ✅ Bridge
-* ✅ Decorator
-* ✅ Composite
-* ✅ Adapter
-* ✅ Flyweight
-* ✅ Facade
-* ✅ Protection Proxy
-* ✅ Virtual Proxy
+✅ Bridge
+
+✅ Decorator
+
+✅ Composite
+
+✅ Adapter
+
+✅ Flyweight
+
+✅ Facade
+
+✅ Protection Proxy
+
+✅ Virtual Proxy
 
 ## S.O.L.I.D
 
-*  ❌ Single Responsibilty Principle  (SRP)
-*  ❌ Open Closed Principle (OCP)
-*  ❌ Liskov Substitution Principle (LSP)
-*  ❌ Interface Segregation Principle (ISP)
-*  ❌ Dependency Inversion Principle (DIP)
+✅ Dependency Inversion Principle (DIP)
+
+❌ Single Responsibilty Principle  (SRP)
+
+❌ Open Closed Principle (OCP)
+
+❌ Liskov Substitution Principle (LSP)
+
+❌ Interface Segregation Principle (ISP)

SOLID.playground/Pages/Dependency Inversion.xcplaygroundpage/Contents.swift

@@ -0,0 +1,52 @@
+//: [Previous](@previous)
+
+import Foundation
+
+// The Problem - Tightly coupled classes
+
+struct Wrong {
+    struct Datastore {
+        // The Datastore should not know something about the Filehandler, it should use an abstraction instead
+        let fileHandler: FileHandler = FileHandler()
+    }
+
+    struct FileHandler {
+        func getFile(name: String) -> Data {
+            return Data()
+        }
+
+        func storeFile(name: String, data: Data) {
+            // Stores the File
+        }
+    }
+}
+
+
+// The Solution - Protocols and DI through the initalizer
+
+protocol FileHandlerProtocol {
+    func getFile(name: String) -> Data
+    func storeFile(name: String, data: Data)
+}
+
+struct Right {
+    struct Datastore {
+        let fileHandler: FileHandlerProtocol
+
+        init(fileHandler: FileHandlerProtocol) {
+            self.fileHandler = fileHandler
+        }
+    }
+
+    struct FileHandler: FileHandlerProtocol {
+        func getFile(name: String) -> Data {
+            return Data()
+        }
+        func storeFile(name: String, data: Data) {
+            // Store the File
+        }
+    }
+}
+
+
+//: [Next](@next)

SOLID.playground/contents.xcplayground

@@ -1,4 +1,2 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<playground version='5.0' target-platform='ios'>
-    <timeline fileName='timeline.xctimeline'/>
-</playground>
+<playground version='6.0' target-platform='ios'/>