ios swift 数组(Array) 基础 - 荔枝

ios swift 基础 合集- 荔枝 点击查看全部

Array 是 集合类型(Collection)的一种。

• 创建数组

var someInts: [Int] = []
var array = ["A","B","C","D","E","F"]

• 用数组字面量构造数组

var shoppingList: [String] = ["Eggs", "Milk"]
// shoppingList 已经被构造并且拥有两个初始项。
var shoppingList = ["Eggs", "Milk"]

• 用下标语法得到数据项

var firstItem = shoppingList[0]

• 修改数组的值

shoppingList[0] = "abc"

• 数组遍历

for item in shoppingList {
  print(item)
}

• 数组合并

var array1 = ["A","B","C"]
var array2 = ["D","E","F"]
var arrTotal = array1 + array2
//["A", "B", "C", "D", "E", "F"]

var array1 = ["A","B","C"]

var array2 = ["D","E","F"]

array1.append(contentsOf: array2)

//array1 = ["A", "B", "C", "D", "E", "F"]

var array1 = ["A","B","C"]
var array2 = ["D","E","F"]
array1 += array2
//array1 = ["A", "B", "C", "D", "E", "F"]

• 示例代码

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

// shoppingList 已经被构造并且拥有两个初始项。shoppingList = ["Eggs", "Milk"]

shoppingList.append("Flour")

// shoppingList 现在有3个数据项，["Eggs", "Milk", "Flour"]

shoppingList += ["Baking Powder"]

// shoppingList 现在有四项了 ["Eggs", "Milk", "Flour", "Baking Powder"]

shoppingList += ["Chocolate Spread", "Cheese", "Butter"]

// shoppingList 现在有七项了 ["Eggs", "Milk", "Flour", "Baking Powder", "Chocolate Spread", "Cheese", "Butter"]

var firstItem = shoppingList[0]

// 第一项是“Eggs”

shoppingList[0] = "Six eggs"

// 其中的第一项现在是“Six eggs”而不是“Eggs” 

//["Six eggs", "Milk", "Flour", "Baking Powder", "Chocolate Spread", "Cheese", "Butter"]

shoppingList[4...6] = ["Bananas", "Apples"]

// shoppingList 现在有6项 

//["Six eggs", "Milk", "Flour", "Baking Powder", "Bananas", "Apples"]

shoppingList.insert("Maple Syrup", at: 0)

// shoppingList 现在有7项

// 现在是这个列表中的第一项是“Maple Syrup”

let mapleSyrup = shoppingList.remove(at: 0)

// 索引值为0的数据项被移除

// shoppingList 现在只有6项，而且不包括 Maple Syrup

// mapleSyrup 常量的值等于被移除数据项“Maple Syrup”

firstItem = shoppingList[0]

// firstItem 现在等于“Six eggs”

let apples = shoppingList.removeLast()

// 数组的最后一项被移除了

// shoppingList 现在只有5项，不包括 Apples

// apples 常量的值现在等于字符串“Apples”

• String ，Array 继承 Collection 区分