diff --git a/Swift/Double.playground/Contents.swift b/Swift/Double.playground/Contents.swift
new file mode 100644
index 0000000..e8c4921
--- /dev/null
+++ b/Swift/Double.playground/Contents.swift
@@ -0,0 +1,115 @@
+import Foundation
+
+public class LinkedList<T> {
+    
+    public class Node<T> {
+        var data: T
+        var next: Node<T>?
+        weak var previous: Node<T>? //  weak to avoid memory leak. ARC do the trick.
+        // Every Node knows only its neighbours
+        
+        init(data: T) {
+            self.data = data
+        }
+    }
+    
+    fileprivate var head: Node<T>?
+    private var tail: Node<T>? // List knows its head and tail.
+    
+    public var isEmpty: Bool {
+        return head == nil
+    }
+    
+    public var first: Node<T>? {
+        return head
+    }
+    
+    public var last: Node<T>? {
+        return tail
+    }
+    
+    public func append(data: T) {
+        let newNode = Node(data: data)
+        if let tailNode = tail {
+            newNode.previous = tailNode
+            tailNode.next = newNode
+        } else {
+            head = newNode
+        }
+        tail = newNode
+    }
+    
+    
+    func removeAll() { // When head and tail is nil, weak ref will automatically delete its references one by one.
+        head = nil
+        tail = nil
+    }
+    
+    public func remove(node: Node<T>) -> T {
+        let prev = node.previous
+        let next = node.next
+        
+        if let prev = prev {
+            prev.next = next
+        } else {
+            head = next
+        }
+        next?.previous = prev
+        
+        if next == nil {
+            tail = prev
+        }
+        
+        node.previous = nil
+        node.next = nil
+        
+        return node.data
+    }
+    
+    
+    public func nodeAt(index: Int) -> Node<T>? {
+        if index >= 0 {
+            var node = head
+            var i = index
+            while node != nil {
+                if i == 0 { return node }
+                i -= 1
+                node = node!.next
+            }
+        }
+        return nil
+    }
+}
+
+extension LinkedList: CustomStringConvertible {
+    
+    public var description: String {
+        
+        var text = "["
+        var node = head
+        
+        while node != nil {
+            text += "\(node!.data)"
+            node = node!.next
+            if node != nil { text += ", " }
+        }
+        
+        return text + "]"
+    }
+}
+
+
+let myList = LinkedList<Int>()
+
+
+myList.append(data: 1231)
+myList.append(data: 3)
+myList.append(data: 5)
+myList.append(data: 10)
+
+print(myList) // [1231, 3, 5, 10]
+let secondNode = myList.nodeAt(index: 1)?.data // 3
+
+myList.removeAll()
+
+print(myList) // []
diff --git a/Swift/Double.playground/contents.xcplayground b/Swift/Double.playground/contents.xcplayground
new file mode 100644
index 0000000..63b6dd8
--- /dev/null
+++ b/Swift/Double.playground/contents.xcplayground
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>
\ No newline at end of file
diff --git a/Swift/Double.playground/playground.xcworkspace/contents.xcworkspacedata b/Swift/Double.playground/playground.xcworkspace/contents.xcworkspacedata
new file mode 100644
index 0000000..919434a
--- /dev/null
+++ b/Swift/Double.playground/playground.xcworkspace/contents.xcworkspacedata
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:">
+   </FileRef>
+</Workspace>
diff --git a/Swift/Double.playground/playground.xcworkspace/xcuserdata/anastasia.xcuserdatad/UserInterfaceState.xcuserstate b/Swift/Double.playground/playground.xcworkspace/xcuserdata/anastasia.xcuserdatad/UserInterfaceState.xcuserstate
new file mode 100644
index 0000000..e5e04c9
Binary files /dev/null and b/Swift/Double.playground/playground.xcworkspace/xcuserdata/anastasia.xcuserdatad/UserInterfaceState.xcuserstate differ