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Swift函數
函數定義
使用 func 定義一個函數。調用函數使用他的名字加 上小括號中的參數列表。使用 -> 分隔參數的名字和 返回值類型。
函數聲明：
func greet(name: String, day: String) -> String {
return "Hello \(name),today is \(day)."
}
函數調用：greet("Bob", "Tuesday")
無返回值函數
func sayGoodbye(personName: String) {
println("Goodbye, \(personName)!")
}
sayGoodbye("Tony")
多返回值函數
使用元組類型返回多個值：
func count(string: String) -> (vowels: Int, consonants:Int, others: Int) {
var vowels = 0,consonants = 0, others= 0 for character in string {
switch String(character).lowercaseString {
case "a","e", "i","o", "u":
++vowels
case "b","c", "d","f", "g", "h", "j", "k", "l", "m","n", "p","q", "r","s", "t", "v", "w","x", "y", "z":
++consonants default:
++others
}
}
return (vowels, consonants, others)
}
let total = count("somearbitrary string!")
println("\(total.vowels) 元音 , \(total.consonants) 輔 音")
嵌入函數
函數嵌套： 相當於函數指針
func chooseStepFunction(backwards: Bool) ->(Int) -> Int {
func stepForward(input: Int) -> Int { return input
+ 1 }
func stepBackward(input: Int) -> Int { return input
- 1 }
return backwards ? stepBackward : stepForward
}
var currentValue = -4
let moveNearerToZero =
chooseStepFunction(currentValue> 0)
while currentValue != 0{
println("\(currentValue)... ")
currentValue = moveNearerToZero(currentValue)
}
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最後更新：2017-04-03 07:57:14