var ap = Array(count:3,repeatedValue: 16)

var ad = Array(count:3,repeatedValue : 15)

var ac = ap + ad

println( ac )

let emptyDic1 = [:]

let emptyDic2 = Dictionary<String,Float>()

@H_502_73@var airports = ["china":"shandong","jinan":"qingdao"]

println(airports)

/*

//add + delete

airports["china"] = "china international"

println(airports)

airports["usa"] = "ny"

println(airports)

//delete 1

airports["usa"] = nil

println(airports)

//delete 2

airports.removeValueForKey("china")

println(airports)

*/

//输出COUNT

println("airports count is "+String(airports.count))

println("airports count is \(airports.count)")

//bianli key

for key in airports.keys {

println(key)

}

//bianli value

for value in airports.values {

println(value)

}

// 把所有的key 和value 转换成数组再输出

let allkeys = Array(airports.keys)

let allvalues = Array(airports.values)

println(allkeys)

println(allvalues)

//元组

let (x,y) = (1,2)

@H_502_73@println("x is \(x) and y is \(y)")

//********

let http404error = (404,"not found")

println(http404error)

//1

let (statusCode,statusMessage) = http404error //采用类型dictionary方式 通过key拿这个value

@H_502_73@println("statusCode is \(statusCode) and statusMessage is \(statusMessage)")

//2

let (justthestatuscode,_) = http404error

println("justthestatuscode is \(justthestatuscode)")

//3

println("status code is \(http404error.0)")

println("message is \(http404error.1)")

let http200status = (statusCode: 200,desc:"ok") //左边是key 右边是value 赋给一个常量

println("the status code is\(http200status.statusCode) and the status message is \(http200status.desc)")

//可选类型 由于toint方法会失败 因此它会返回一个可选的int类型 而不同于int类型，一个可选的类型 返回的是一个int或者不存在

var serverResponseCode : Int? = 404

let possiblenumber = "123"

let convertednumber: Int? = possiblenumber.toInt()

var responsecode:Int? = 404 // 要么存在 且为404

responsecode = nil // 要么不存在 可以赋值为nil表示

//可选类型的nil和oc中的nil不一样 swift的nil不可用于非可选类型

//特定类型的值不存在 任何类型的可选类型都能赋值为nil 如果代码中的变量常量需要适配值不存在的情况，务必将他声明为可选类

//3.如果定义的【可选类型】的不提供默认值，该对象自动设为nil 但是常量变量定义需要默认值

// var strvalue = nir 不可以false错误

var strvalue:String? //default=nil

//let hashValue = strvalue?.hashValue //方法调用 ？是否响应后面的方法 存在就响应 不存在 就不响应 就不赋值给常量

println("hashvalue is \(strvalue?.hashValue)")

//解包！

let possiblestring:String? = "an optional string"

println(possiblestring!) //解包 我确定possiblestring的值确定存在

let stringValue = possiblestring!.hashValue //哈希值：hashvalue 必须解包 才能获取可选量的值

//or println(possiblestring!.hashValue)

println(stringValue)

//optional binding =上一行 好麻烦。。

if let svalue = possiblestring{

let stringvalue = svalue.hashValue

}

//隐式解包 后面用的时候不用加感叹号了！直接在定义的时候加感叹号

let assumestring : String! = "an lalalala"

println(assumestring)

println(assumestring.hashValue)

原文链接：https://www.f2er.com/swift/325824.html