diff --git a/pre-work.playground/Contents.swift b/pre-work.playground/Contents.swift
new file mode 100644
index 0000000..fcd684e
--- /dev/null
+++ b/pre-work.playground/Contents.swift
@@ -0,0 +1,83 @@
+/* Natalie Polk
+ * May 19, 2016
+ * i_X iOS Development S1
+ * Code Challenge
+ */
+
+
+
+
+import UIKit
+
+
+/* ----------------------- Challenge 1 (1 star) ------------------------ */
+
+func swaps<T>(inout a:T, inout with b:T) {
+    (a, b) = (b, a)
+}
+
+var a = "Natalie", b = "Polk"
+swaps(&a, with: &b)
+[a, b]
+
+
+
+/* ----------------------- Challenge 2 (2 stars) ----------------------- */
+
+func flexStrings(s1:String = "", s2:String = "") -> String {
+    if s1.isEmpty && s2.isEmpty {
+        return "none"
+    }
+    else {
+        return s1+s2
+    }
+}
+
+flexStrings() //--> "none"
+flexStrings("One") //--> "One"
+flexStrings("One", s2: "Two") //--> "OneTwo"
+
+
+
+/* ----------------------- Challenge 3 (3 stars) ----------------------- */
+
+func sumAny(a:Any...) -> String {
+    var sum = 0;
+    for this in a {
+        switch this {
+        case let someInt as Int :
+            if someInt == 0 {
+                sum = sum-10
+            }
+            else {
+                sum = sum+someInt
+            }
+        case let someString as String :
+            if someString.isEmpty {
+                sum-=10
+            }
+            else if Int(someString) != nil && Int(someString) >= 0 {
+                sum += Int(someString)!
+            }
+        default : break
+        }
+    }
+    return String(sum)
+}
+
+let resultEmpty = sumAny() //--> "0"
+let result1 = sumAny(Double(), 10, "-10", 2) //--> "12"
+let result2 = sumAny("Marin Todorov", 2, 22, "-3", "10", "", 0, 33, -5) //--> "42"
+
+
+
+/* ----------------------- Challenge 4 (3 stars) ----------------------- */
+
+func countFrom(from:Int, to: Int) {
+    if from <= to {
+        print(from)
+        countFrom(from+1, to: to)
+    }
+}
+
+countFrom(1, to: 7)
diff --git a/pre-work.playground/contents.xcplayground b/pre-work.playground/contents.xcplayground
new file mode 100644
index 0000000..5da2641
--- /dev/null
+++ b/pre-work.playground/contents.xcplayground
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>
\ No newline at end of file
diff --git a/pre-work.playground/playground.xcworkspace/contents.xcworkspacedata b/pre-work.playground/playground.xcworkspace/contents.xcworkspacedata
new file mode 100644
index 0000000..919434a
--- /dev/null
+++ b/pre-work.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/pre-work.playground/playground.xcworkspace/xcuserdata/serenemirza.xcuserdatad/UserInterfaceState.xcuserstate b/pre-work.playground/playground.xcworkspace/xcuserdata/serenemirza.xcuserdatad/UserInterfaceState.xcuserstate
new file mode 100644
index 0000000..551b8ec
Binary files /dev/null and b/pre-work.playground/playground.xcworkspace/xcuserdata/serenemirza.xcuserdatad/UserInterfaceState.xcuserstate differ