swift的语法小demo5(for循环，元组)

 

import Foundation

/*
    swift可以return一个元组，好像挺有用的，也就是说可以返回一个对象所有的键值对
*/
let http404Error = (404,"not found")
let (statusCode,statusMessage) = http404Error
println("\(statusCode)  \(statusMessage)")


let (justTheStatusCode,_) = http404Error
println("\(justTheStatusCode)")

println("\(http404Error.0)  \(http404Error.1)")

let http200Status = (statusCode:200,description:"ok")
println("\(http200Status.0)  \(http200Status.1)")
println("\(http200Status.statusCode)  \(http200Status.description)")

let possibleNumber = "123w"
let convertedNumber = possibleNumber.toInt()
if convertedNumber {
    println("\(convertedNumber!) ee")
}

//assert使用场景：当必须保证age小于0时，可以加上assert方法确保万无一失
let age = -3
assert(age <= 0, "A person's age cannot be less than zero")

/*
    循环：for两个点和三个点的区别
*/
for index in 1...5{
    println("\(index)")
}
for index in 1..5{
    println("\(index)")
}