Swift Tour 随笔总结 (2)
2024-08-25 07:37:57
Type Aliases
typealias AudioSample = UInt16
Booleans
非boolean值不会被替代为bool,例如:
let i = 1
if 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) = heep404Error
println("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, _) = http404Error
println("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)")
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