Swift 集合类型之数组

数组是有序的，并且数组中的元素是同一种类型

创建空数组

import UIKit

// 创建空数组
var someInts = [Int]()
print("someInts is of type [Int] with \(someInts.count) items.")

// 数组尾部添加元素
someInts.append(3)

someInts = []

创建有元素数组

// 创建有数组数组
var threeDoubles = Array(count: 3, repeatedValue: 0.0)

var anotherThreeDoubles = Array(count: 3, repeatedValue: 2.5)

var sixDoubles = threeDoubles + anotherThreeDoubles

var shoppingList = ["Eggs", "Milk"]

print("The shopping list contains \(shoppingList.count) items.")

if shoppingList.isEmpty {
    print("The shopping list is empty")
} else {
    print("The shopping list is not empty")
}

数组添加元素

// 数组添加元素
shoppingList.append("Flour")
print(shoppingList)

shoppingList += ["Baking Powder"]
print(shoppingList)

shoppingList += ["Chocolate Spread", "Cheese", "Butter"]
print(shoppingList)

console log结果如下:

数组添加元素.png

数组的增删改访问操作

// 数组访问元素
var firstItem = shoppingList[0]
print(firstItem)

// 修改元素值
shoppingList[0] = "Six Eggs"
print(shoppingList)

shoppingList[4...6] = ["Bananas", "Apples"]
print(shoppingList)

// 插入元素
shoppingList.insert("Maple Syrup", atIndex: 0)
print(shoppingList)

// 移除元素
let mapleSyrup = shoppingList.removeAtIndex(0)
print(mapleSyrup)
print(shoppingList)

// 移除最后一个元素
let lastItem = shoppingList.removeLast()
print(lastItem)
print(shoppingList)

console log结果如下:

数组的增删改访问.png

数组的遍历

// 遍历数组
for item in shoppingList{
    print(item)
}

for (index, value) in shoppingList.enumerate() {
    print("Item \(index + 1): \(value)")
}

console log结果如下:

数组的遍历.png