Swift心得笔记之控制流

let anotherCharacter: Character = "a"

switch anotherCharacter {
case "a":
  println("The letter a")
case "A":
  println("The letter A")
default:
  println("Not the letter A")
}

let somePoint = (1, 1)

switch somePoint {
case (0, 0):  // 位于远点
  println("(0, 0) is at the origin")
case (_, 0):  // x为任意值，y为0，即在 X 轴上
  println("(\(somePoint.0), 0) is on the x-axis")
case (0, _):  // y为任意值，x为0，即在 Y 轴上
  println("(0, \(somePoint.1)) is on the y-axis")
case (-2...2, -2...2): // 在以原点为中心，边长为4的正方形内。
  println("(\(somePoint.0), \(somePoint.1)) is inside the box")
default:
  println("(\(somePoint.0), \(somePoint.1)) is outside of the box")
}

// "(1, 1) is inside the box"

let somePoint = (0, 1)

switch somePoint {
case (0, 0):
  println("(0, 0) is at the origin")
case (let x, 0):
  println("x is \(x)")
case (0, let y):
  println("y is \(y)")
default:
  println("default")
}

let yetAnotherPoint = (1, -1)

switch yetAnotherPoint {
case let (x, y) where x == y:
  println("(\(x), \(y)) is on the line x == y")
case let (x, y) where x == -y:
  println("(\(x), \(y)) is on the line x == -y")
case let (x, y):
  println("(\(x), \(y)) is just some arbitrary point")
}
// "(1, -1) is on the line x == -y”

// for loop (array)
let myArray = [1, 1, 2, 3, 5]
for value in myArray {
  if value == 1 {
    println("One!")
  } else {
    println("Not one!")
  }
}

// for loop (dictionary)
var dict = [
  "name": "Steve Jobs",
  "title": "CEO",
  "company": "Apple"
]
for (key, value) in dict {
  println("\(key): \(value)")
}

// for loop (range)
for i in -1...1 { // [-1, 0, 1]
  println(i)
}
// use .. to exclude the last number

// for loop (ignoring the current value of the range on each iteration of the loop)
for _ in 1...3 {
  // Do something three times.
}

// while loop
var i = 1
while i < 1000 {
  i *= 2
}

// do-while loop
do {
  println("hello")
} while 1 == 2

// Switch
let vegetable = "red pepper"
switch vegetable {
case "celery":
  let vegetableComment = "Add some raisins and make ants on a log."
case "cucumber", "watercress":
  let vegetableComment = "That would make a good tea sandwich."
case let x where x.hasSuffix("pepper"):
  let vegetableComment = "Is it a spicy \(x)?"
default: // required (in order to cover all possible input)
  let vegetableComment = "Everything tastes good in soup."
}

// Switch to validate plist content
let city:Dictionary<String, AnyObject> = [
  "name" : "Qingdao",
  "population" : 2_721_000,
  "abbr" : "QD"
]
switch (city["name"], city["population"], city["abbr"]) {
  case (.Some(let cityName as NSString),
    .Some(let pop as NSNumber),
    .Some(let abbr as NSString))
  where abbr.length == 2:
    println("City Name: \(cityName) | Abbr.:\(abbr) Population: \(pop)")
  default:
    println("Not a valid city")
}