Swift中文教程(三)--流程控制

 1 let individualScores = [75, 43, 103, 87, 12]
 2 var teamScore = 0
 3 for score in individualScores {
 4     if score > 50 {
 5         teamScore += 3
 6     } else {
 7         teamScore += 1
 8     }
 9 }
10 teamScore

var optionalString: String? = "Hello"
optionalString == nil
 
var optionalName: String? = "John Appleseed"
var greeting = "Hello!"
if let name = optionalName {
    greeting = "Hello, \(name)"
}

 1 let vegetable = "red pepper"
 2 switch vegetable {
 3 case "celery":
 4     let vegetableComment = "Add some raisins and make ants on a log."
 5 case "cucumber", "watercress":
 6     let vegetableComment = "That would make a good tea sandwich."
 7 case let x where x.hasSuffix("pepper"):
 8     let vegetableComment = "Is it a spicy \(x)?"
 9 default:
10     let vegetableComment = "Everything tastes good in soup."
11 }

 1 let interestingNumbers = [
 2     "Prime": [2, 3, 5, 7, 11, 13],
 3     "Fibonacci": [1, 1, 2, 3, 5, 8],
 4     "Square": [1, 4, 9, 16, 25],
 5 ]
 6 var largest = 0
 7 for (kind, numbers) in interestingNumbers {
 8     for number in numbers {
 9         if number > largest {
10             largest = number
11         }
12     }
13 }
14 largest

 1 var n = 2
 2 while n < 100 {
 3     n = n * 2
 4 }
 5 n
 6  
 7 var m = 2
 8 do {
 9     m = m * 2
10 } while m < 100
11 m

 1 var firstForLoop = 0
 2 for i in 0..3 {
 3     firstForLoop += i
 4 }
 5 firstForLoop
 6  
 7 var secondForLoop = 0
 8 for var i = 0; i < 3; ++i {
 9     secondForLoop += 1
10 }
11 secondForLoop