Swift数组详细用法解析

  • Z时代
  • 2024-01-10
  • 分类：综合

一、说明

Swift数组中的类型必须一致，这一点与OC不同

// 数组初始化
var numbers = [0,1,2,3,4,5]
var vowels = ["A","E","I","O","U"]
// 数组的类型： [Int] 或者 Array<Int>
//var numbers: [Int] = [0,1,2,3,4,5]
//var numbers: Array<Int> = [0,1,2,3,4,5]
// 空数组
var emptyArray1:[Int] = []
var emptyArray2:Array<Int> = []
var emptyArray3 = [Int]()
var emptyArray4 = Array<Int>()
// 创建具有默认值的数组(相同元素的数组)
var allZeros = Array<Int>(repeating: 0, count: 5)
//[0,0,0,0,0]
var allZeros2 = [Int](repeating: 0, count: 5)
//[0,0,0,0,0]

二、常用方法

var numbers = [1,2,3,4,5]
var vowels = ["A","E","I","O","U"]
var emptyArray = [Int]()
// 数组长度
vowels.count
// 判空
numbers.isEmpty
emptyArray.isEmpty
// 获取元素
vowels[2]
// 数组越界是一个严重的错误
//vowels[-1]
//vowels[5]
// 获取第一个元素和最后一个元素，返回的是可选型
vowels.first 
vowels.last  //.first和.last的返回值都为可选型
emptyArray.first
if let firstVowel = vowels.first{
  print("The first vowel is " + firstVowel)
}
vowels.first!
vowels[vowels.count-1]
// 获取最小，最大值
numbers.min() //1
vowels.max() //U
// 使用范围
numbers[2..<4] //[3,4]
numbers[2..<numbers.count] //[3,4,5]
// 包含
vowels.contains("A")
vowels.contains("B")
let letter = "A"
if vowels.contains( letter ){
  print("\(letter) is a vowel")
}
else{
  print("\(letter) is not a vowel")
}
vowels.index(of: "E") //获取索引，返回值为可选型
if let index = vowels.index(of: "E"){
  print("E is a vowel in position \(index+1).")
}
else{
  print("E is not a vowel.")
}
// 遍历
for index in 0..<numbers.count{
  numbers[index]
}
for number in numbers{
  print(number)
}
for (index, vowel) in vowels.enumerated(){
  //遍历数组索引和元素
  print("\(index+1): \(vowel)")
}
// 比较
var oneToFive = [1,2,3,4,5]
numbers == oneToFive //true
var oneToFive2 = [1,2,4,3,5]
numbers == oneToFive //true
//swift 3.0之前数组是有序的数据集合，swift 3.0后为无序

三、更多操作

var courses = ["A","B","C"]
// 添加元素
courses.append("D") //["A","B","C","D"]
print(courses)
// 数组常量
//使用let定义的数组不可以更改任何内容
courses += ["E"] //+=后面必须和前面的类型一致 //["A","B","C","D","E"]
print(courses)
// 两个数组相加
courses = courses + ["F","G"] //+后面必须是数组
//["A","B","C","D","E","F","G"]
print(courses)
courses.insert("Q", at: 5) 
//["A", "B", "C", "D", "E", "Q", "F", "G"]
print(courses)
// 删除元素
courses.removeLast()
//["A", "B", "C", "D", "E", "Q", "F"]
print(courses)
courses.removeFirst()
//["B", "C", "D", "E", "Q", "F"]
print(courses)
courses.remove(at: 4)
//["B", "C", "D", "E", "F"]
//courses.removeAtIndex(10)
print(courses)
//区间删除操作
//courses.removeRange(0..<4)
//courses.removeRange(0..<10)
//print(courses)
//courses.removeAll()
//print(courses)
// 修改元素
courses[0] = "W"
//["W", "C", "D", "E", "F"]
print(courses)
//范围修改
courses[1...3] = ["W","W","W"]
//["W", "W", "W", "W", "F"]
print(courses)
courses[0...3] = ["W"]
//["W", "F"]
print(courses)

四、二维数组

var board = [ [1024,16,2,0] , [256,4,2,0] , [64,2,0,0] , [2,0,0,0] ]
//var board:[[Int]] = [ [1024,16,2,0] , [256,4,2,0] , [64,2,0,0] , [2,0,0,0] ]
//var board:[Array<Int>] = = [ [1024,16,2,0] , [256,4,2,0] , [64,2,0,0] , [2,0,0,0] ]
//var board:Array<[Int]> = [ [1024,16,2,0] , [256,4,2,0] , [64,2,0,0] , [2,0,0,0] ]
//var board:Array<Array<Int>> = [ [1024,16,2,0] , [256,4,2,0] , [64,2,0,0] , [2,0,0,0] ]
// 二维数组获取元素
board[0]
board[0][0]
// 获取二维数组两个维度的信息
board.count
board[0].count
// Swift中的二维数组，每一维度的元素数目可以不同
board[0].append(0)
board
// 为二维数组的第一个维度添加的元素是一个数组
board.append([0,0,0,0])
board += [ [0,0,0,0] ]
board

五、NSArray

NSArray是一个类，Array是一个结构体

var array1 = [] //会默认是NSArray,swift3.0之后该写法废除
var array2 = [1,2,3,4,5] as NSArray
var array3: NSArray = [1,"hello"]
var array4: [NSObject] = [1 as NSObject,"hello" as NSObject]

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