Add tasks for all the new languages

Task/Run-length-encoding/Swift/run-length-encoding-1.swift

@@ -0,0 +1,14 @@
+import Foundation
+
+// "WWWBWW" -> [(3, W), (1, B), (2, W)]
+func encode(input: String) -> [(Int, Character)] {
+    return input.characters.reduce([(Int, Character)]()) {
+        if $0.last?.1 == $1 { var r = $0; r[r.count - 1].0++; return r }
+        return $0 + [(1, $1)]
+    }
+}
+
+// [(3, W), (1, B), (2, W)] -> "WWWBWW"
+func decode(encoded: [(Int, Character)]) -> String {
+    return encoded.reduce("") { $0 + String(count: $1.0, repeatedValue: $1.1) }
+}

Task/Run-length-encoding/Swift/run-length-encoding-2.swift

@@ -0,0 +1,3 @@
+let input = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW"
+let output = decode(encode(input))
+print(output == input)

Task/Run-length-encoding/Swift/run-length-encoding-3.swift

@@ -0,0 +1,15 @@
+// "3W1B2W" -> "WWWBWW"
+func decode(encoded: String) -> String {
+    let scanner = NSScanner(string: encoded)
+    var char: NSString? = nil
+    var count: Int = 0
+    var out = ""
+
+    while scanner.scanInteger(&count) {
+        while scanner.scanCharactersFromSet(NSCharacterSet.letterCharacterSet(), intoString: &char) {
+            out += String(count: count, repeatedValue: Character(char as! String))
+        }
+    }
+
+    return out
+}

Task/Run-length-encoding/Swift/run-length-encoding-4.swift

@@ -0,0 +1,4 @@
+let encodedString = encode(input).reduce("") { $0 + "\($1.0)\($1.1)" }
+print(encodedString)
+let outputString = decode(encodedString)
+print(outputString == input)