SwiftTour随笔总结(2)

Type Aliases

typealias AudioSample = UInt16

Booleans

非boolean值不会被替代为bool，例如：

let i = 1if i {　　// this example will not compile, and will report an error}

Tuples

例如：HTTPStatus Code ("404", "Not Found")

let http404Error = (404, "Not Found")// http404Error is of type (Int, String)

access Tuple:

let (statusCode, statusMessage) = heep404ErrorPRintln("This status code is /(statusCode)")// prints "The status code is 404"println("The statuis message is /(statusMessage)")// prints "The status message is Not Found"

简写，使用 _ 代替不需要的变量，例如：

let (justTheStatusCode, _) = http404Errorprintln("The status code is /(justTheStatusCode)")// prints "The status code is 404"

另一种access tuple的方法：

println("The status code is /(http404Error.0)")// prints "The status code is 404"println("The status message is /(http404Error.1)")// prints "The status message is Not Found"

Tuple的完整define

let http200Status = (statusCode: 200, description: "OK")

对应的access

println("The status code is /(http200status.statusCode)")println("The status code message is /(http200status.description)")