feat: [Swift] Language cheatsheet is added.

mobile/swift.swift

@@ -0,0 +1,186 @@
+/********************************************************************************************
+ * Swift CHEATSHEET
+ * https://www.swift.org 
+ ********************************************************************************************/
+
+// Variables
+  var myInt = 1
+  var myExplicitInt: Int = 1 // explicit type
+  var x = 1, y = 2, z = 3 // declare multiple integers
+  myExplicitInt = 2 // set to another integer value
+
+// Constants
+  let myInt = 1
+  myInt = 2 // compile-time error!
+  
+// Strings
+  var myString = "a"
+  let myImmutableString = "c"
+  myString += "b" // ab
+  myString = myString + myImmutableString // abc
+  myImmutableString += "d" // compile-time error!
+
+  let count = 7
+  let message = "There are \(count) days in a week"
+  Logical Operators
+  var happy = true
+  var sad = !happy // logical NOT, sad = false
+  var everyoneHappy = happy && sad // logical AND, everyoneHappy = false
+  var someoneHappy = happy || sad // logical OR, someoneHappy = true
+
+// Printing
+  let name = "swift"
+  println("Hello")
+  println("My name is \(name)")
+  print("See you ")
+  print("later")
+  /*  Hello
+      My name is swift
+      See you later 
+  */
+
+// Arrays
+  var colors = ["red", "blue"]
+  var moreColors: String[] = ["orange", "purple"] // explicit type
+  colors.append("green") // [red, blue, green]
+  colors += "yellow" // [red, blue, green, yellow]
+  colors += moreColors // [red, blue, green, yellow, orange, purple]
+
+  var days = ["mon", "thu"]
+  var firstDay = days[0] // mon
+  days.insert("tue", atIndex: 1) // [mon, tue, thu]
+  days[2] = "wed" // [mon, tue, wed]
+  days.removeAtIndex(0) // [tue, wed]
+  Dictionaries
+  var days = ["mon": "monday", "tue": "tuseday"]
+  days["tue"] = "tuesday" // change the value for key "tue"
+  days["wed"] = "wednesday" // add a new key/value pair
+
+  var moreDays: Dictionary = ["thu": "thursday", "fri": "friday"]
+  moreDays["thu"] = nil // remove thu from the dictionary
+  moreDays.removeValueForKey("fri") // remove fri from the dictionary
+  Conditionals
+
+// IF STATEMENT
+  let happy = true
+  if happy {
+      println("We're Happy!")
+  } else {
+      println("We're Sad :('")
+}
+
+// We're Happy!
+
+  let speed = 28
+  if speed <= 0 {
+      println("Stationary")
+  } else if speed <= 30 {
+      println("Safe speed")
+  } else {
+      println("Too fast!")
+  }
+
+// Safe speed
+
+
+// SWITCH STATEMENT
+  let n = 2
+  switch n {
+  case 1:
+      println("It's 1!")
+  case 2...4:
+      println("It's between 2 and 4!")
+  case 5, 6:
+      println("It's 5 or 6")
+  default:
+      println("Its another number!")
+  }
+
+// It's between 2 and 4!
+  For Loops
+  for var index = 1; index < 3; ++index {
+    // loops with index taking values 1,2 
+  }
+  for index in 1..3 {
+    // loops with index taking values 1,2
+  }
+  for index in 1...3 { 
+    // loops with index taking values 1,2,3
+  }
+
+  let colors = ["red", "blue", "yellow"]
+  for color in colors {
+      println("Color: \(color)")
+  }
+  // Color: red
+  // Color: blue
+  // Color: yellow 
+
+  let days = ["mon": "monday", "tue": "tuesday"]
+  for (shortDay, longDay) in days {
+      println("\(shortDay) is short for \(longDay)")
+  }
+  // mon is short for monday
+  // tue is short for tuesday
+  While Loops
+  var count = 1
+  while count < 3 {
+      println("count is \(count)")
+      ++count
+  }
+  // count is 1
+  // count is 2
+
+  count = 1
+  while count < 1 {
+      println("count is \(count)")
+      ++count
+  }
+  //
+
+
+  count = 1
+  do {
+      println("count is \(count)")
+      ++count
+  } while count < 3
+  // count is 1
+  // count is 2
+
+count = 1
+do {
+    println("count is \(count)")
+    ++count
+} while count < 1
+
+// count is 1
+
+// Functions
+  func iAdd(a: Int, b: Int) -> Int {
+    return a + b
+  }
+  iAdd(2, 3) // returns 5
+
+  func eitherSide(n: Int) -> (nMinusOne: Int, nPlusOne: Int) {
+    return (n-1, n+1)
+  }
+  eitherSide(5) // returns the tuple (4,6)
+
+// Classes
+  class Counter {
+    var count: Int = 0 
+    func inc() { 
+      count++
+    }
+    func add(n: Int) {
+      count += n
+    }
+    func printCount() {
+      println("Count: \(count)")
+    }
+  }
+
+  var myCount = Counter()
+  myCount.inc()
+  myCount.add(2)
+  myCount.printCount() // Count: 3