Swift编程中的switch...case语句实例解析

var rank = "A"
switch rank{
  case "A": //相当于if
    print("优")
  case "B": // 相当于else if
    print("优")
  case "C": // 相当于else if
    print("优")
  default: // 相当于else
    print("没有评级")
}

var rank1 = "A"
switch rank1{
  case "A":
  case "B":
    print("优")
  case "C":
    print("优")
  default:
    print("没有评级")
}

var rank1 = "A"
switch rank1{
  case "A", "B": // 注意OC不能这样写
    print("优")
  case "C":
    print("差")
  default:
    print("没有评级")
}

var rank2 = "A"
switch rank2{
  case "A":
    print("优")
  case "B":
    print("良")
  case "C":
    print("差")
}

var rank3 = "A"
switch rank3{
  default:
    print("没有评级")
  case "A":
    print("优")
  case "B":
    print("良")
  case "C":
    print("差")
}

var rank4 = "A"
switch rank4{
  case "A":
    var num = 10
    print("优")
  case "B":
    print("良")
  case "C":
    print("差")
  default:
    print("没有评级")
}

var num = 10;
switch num{
  case 1...9:
    print("个位数")
  case 10...99:
    print("十位数")
  default:
    print("其它数")
}

var point = (10, 15)
switch point{
  case (0, 0):
    print("坐标在原点")
  case (1...10, 10...20): // 可以在元祖中再加上区间
    print("坐标的X和Y在1~10之间")
  case (_, 0): // X可以是任意数
    print("坐标的X在X轴上")
  default:
    print("Other")
}

var point = (1, 10)
switch point{
  case (var x, 10): // 会将point中X的值赋值给X
    print("x= \(x)")
  case (var x, var y): // 会将point中XY的值赋值给XY
    print("x= \(x) y= \(y)")
  case var( x, y):
    print("x= \(x) y= \(y)")
  default:
    print("Other")
}

var point = (100, 10)
switch point{
  // 只有where后面的条件表达式为真才赋值并执行case后的语句
  case var(x, y) where x > y: 
    print("x= \(x) y= \(y)")
  default:
    print("Other")
}

let integerToDescribe = 5 
var description = "The number \(integerToDescribe) is" 
switch integerToDescribe { 
case 2, 3, 5, 7, 11, 13, 17, 19: 
  description += " a prime number, and also" 
  fallthrough 
default: 
  description += " an integer." 
} 
println(description) 
// prints "The number 5 is a prime number, and also an integer."