Swift 学习笔记 「控制流」

###For 循环

• for-in 循环

    for index in 1...5 {...}
  

  如果你不需要循环中产生的值，你可以用下划线来忽视它

    for _ in 1...power{...}
  

• for-condition-increment 循环

###Switch

• 每个 case 下都必须至少有一个执行语句。

• 范围匹配

    let count = 3000
    switch count{
    case 0:
        ...
    case 1...9:
        ...
    case 10...99:
        ...
    case 100...999:
        ...
    default:
        ...
    }	
  

• 元组匹配，你可以用下划线来匹配任何可能的值

    let somePoint = (1, 1)
    switch somePoint {
    case(0, 0):
        ...
    case(_, 0):
        ...
    case(0, _):
        ...
    case( -2...2, -2...2):
        ...
    default:
        ...
    }
  

• 绑定值

    let anotherPoint = (2, 0)
    switch anotherPoint {
    case(let x, 0):
        ...
    case(0, let y):
        ...
    case let(x, y):
        ...
    }
  

• where：switch 中的 case 可以通过 where 来进行更多的判断条件

    let yetAnotherPoint = (1, -1)
    switch yetAnotherPoint {
    case let(x, y) where x == y:
        ...
    case let(x, y) where x == -y:
        ...
    case let(x, y):
        ...
    }
  

###Fallthrough

使用 fallthrough 来获得和 C 中 switch 一样的体验。

let interger = 5
switch interger{
case 5:
	...
	fallthrough
default:
	...
}

###带标签的语句

给语句带上标签，可以是 continue 和 break 直接影响标签循环

gameLoop: while square != finalSquare {
	switch square + diceRoll {
	case finalSquare:
		...
		break gameLoop
	case let newSquare where newSquare > finalSquare:
		...
		continue gameLoop
	default:
		...
	}
}

END