// Playground - noun: a place where people can play

import UIKit

// 数组 字典

// 集合的可变性 赋值给var的集合是可变的mutable，赋值给let的集合是不可变的immutable

// 数组   Array<SomeType> 等价于 [SomeType]

var shoppingList : [String] = ["Eggs", "Milk"] // var shoppingList = ["Eggs", "Milk"] 自动推断类型

// 数组计数

println("the shopping list contains \(shoppingList.count) items")

// 检查数组是否为空

if shoppingList.isEmpty {

    println("the shopping list is empty")

} else {

    println("the shopping list is not empty")

}

// 向数组中添加元素

shoppingList.append("Flour")

shoppingList += ["Baking Powder"]

// 访问数组中元素

var firstItem = shoppingList[]

// 批量替换数组中元素 用于替换的数组元素个数与替换的范围不一定要相同

shoppingList[...] = ["Apples"]

// 插入元素

shoppingList.insert("Maple Syrup", atIndex: )

// 从数组中移除元素

let mapleSyrup = shoppingList.removeAtIndex()

shoppingList.removeRange(Range(start: , end: ))

shoppingList.removeLast()

// 遍历数组

for item in shoppingList {

    println(item)

}

for (index, item) in enumerate(shoppingList) {

    println("Item \(index + 1): \(item)")

}

// 创建并初始化数组

var someInts = [Int]()

println("someInts is of type [Int] with \(someInts.count) items")

// 创建数组时赋默认值

var thressDoubles = [Double](count: , repeatedValue: 0.0)

// 组合数组

var anotherDoubles = [Double](count: , repeatedValue: 0.1)

var eightDouble = thressDoubles + anotherDoubles

// 字典

//Dictionary<key, value>  [key  : value]

var airports: [String : String] = ["YYZ" : "Toronto Pearson", "DUB" : "Dublin"] // var airports = ["YYZ" : "Toronto Pearson", "DUB" : "Dublin"]

// 访问、修改字典

println("The airports dictionary contains \(airports.count) items")

if airports.isEmpty {

    println("The airports dictionary is empty")

} else {

    println("The airports dictionary is not empty")

}

// 添加元素

airports["LHR"] = "London"

airports["LHR"] = "London Heathrow"

// 通过方法设置键值. 返回被替换的value optional

let oldValue = airports.updateValue("Dublin Airport", forKey: "DUB")

// 移除键值对

airports["DUB"] = nil

airports.removeValueForKey("DUB")

// 遍历

for (key, value) in airports {

    println("key: \(key), value: \(value)")

}