Swift基础1_简单数据类型和循环

最新推荐文章于 2025-08-12 21:06:13 发布

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#swift #数据类型 #循环 #数组字典 #switch

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本文介绍了Swift编程语言的基础概念，包括变量与常量定义、显示指定类型、数组和字典的操作，以及如何创建和初始化数组与字典。此外，还详细讲解了数组添加元素的方法、for循环和switch语句的应用。

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1 常量变量

var myVariable = 42 //变量
myVariable = 50
let myConstant = 42 //常量

2 显示指明变量类型

let explicitDouble: Double = 70

3 数组和字典

var shoppingList = ["catfish", "water", "tulips", "blue paint"] 
shoppingList[1] = "bottle of water" 
  
var occupations = [ 
    "Malcolm": "Captain", //前面是key 后面是value
    "Kaylee": "Mechanic", 
] 
occupations["Jayne"] = "Public Relations"

4 创建初始化数组和字典

let emptyArray = String[]() 
let emptyDictionary = Dictionary<String, Float>()

5数组添加

var emptyarry = String[]()
emptyarry.append("dfd")

6 for循环

let sss = [11,12,43,554,12,434]
for i in 0..4 {
     print("\(i) = \(sss[i])");
         print("\n");
      }
for i in sss{
      print(i);
         print("\n");
      }

7switch

let vegetable = "red pepper" 
switch vegetable { 
case "celery": 
    let vegetableComment = "Add some raisins and make ants on a log." 
case "cucumber", "watercress": 
    let vegetableComment = "That would make a good tea sandwich." 
case let x where x.hasSuffix("pepper"): 
    let vegetableComment = "Is it a spicy \(x)?" fallthrough 
default: 
    let vegetableComment = "Everything tastes good in soup." 
}