Swift Ninja Challenges - I had some trouble with the third one, but they were fun!

swiftNinjaChallenge1.playground/Contents.swift

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+//: Playground - noun: a place where people can play
+
+import UIKit
+
+// Your first challenge is to write a function that takes two variables (of any type) as
+// parameters and swaps their values.
+// Need to use inout keyword so that the values can be changed outside of the function scope.
+func swapper<Type>(inout a: Type, inout _ b: Type)
+{
+    (a, b) = (b, a)
+}
+
+var a = "first"
+var b = "second"
+// Call the function
+swapper(&a, &b)
+
+print(a)
+print(b)

swiftNinjaChallenge1.playground/contents.xcplayground

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

swiftNinjaChallenge3.playground/Contents.swift

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+//: Playground - noun: a place where people can play
+
+import UIKit
+
+// Single return statement.
+func sumAny(anys: Any...) -> String {
+    return String((anys.map({item in
+        switch item {
+        case "" as String, 0 as Int:
+            return -10
+        case let s as String where Int(s) > 0:
+            return Int(s)!
+        case is Int:
+            return item as! Int
+        default:
+            return 0
+        }
+    }) as [Int]).reduce(0) {
+        // Reformat to String
+        $0 + $1
+        })
+}
+
+sumAny(5, "5", "dad?", "5.0")

swiftNinjaChallenge3.playground/contents.xcplayground

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

swiftNinjaChallenge4.playground/Contents.swift

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+//: Playground - noun: a place where people can play
+
+import UIKit
+
+// Resursvely count from from to to
+func countFrom(from: Int, to: Int)
+{
+    print(from, terminator: "")
+
+    if (from < to) {
+        countFrom(from + 1, to: to)
+    }
+}
+
+countFrom(1, to: 5)

swiftNinjaChallenge4.playground/contents.xcplayground

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

swiftNinjaProgress

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+challenge 1:
+	2 stars
+challenge 2:
+	3 stars
+challenge 3:
+	1 star
+challenge 4:
+	2 stars
+

swiftNinjachallenge2.playground/Contents.swift

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+//: Playground - noun: a place where people can play
+
+import UIKit
+
+// Concetenate the arguments if they exist. 
+func flexStrings(s1: String?=nil, _ s2: String?=nil) -> String
+{
+    if s1 == nil {
+        return "none"
+    }
+    else if s2 == nil{
+        return s1!
+    }
+    else {
+        return s1! + s2!
+    }
+}
+
+// Their faster implementation
+func betterFlexStrings(s1: String = "", _ s2: String = "") -> String {
+    return s1 + s2 == "" ? "none": s1 + s2
+}
+
+var s1 = "One", s2 = "Two"
+
+print(flexStrings(s1, s2))
+

swiftNinjachallenge2.playground/contents.xcplayground

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