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用 10 个简单的代码片段介绍 Swift

 1 year ago
source link: https://www.fly63.com/article/detial/12605
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1.变量的声明和初始化

var myVariable = 42

2. 常量的声明和初始化

let mynumber = 5

3. 连接字符串

var mytext = "My name is "
var name = "John"
var sentence = mytext + name

4. 在字符串内执行操作

let age = 44
let mytext = "My name is John and I am \(age) years old"

5.声明一个Int类型的可选变量

var mynumber: Int?

6. 解包同名的可选值

var count = 0
var mynumber: Int? = 5
if let mynumber {
    count = count + mynumber
}
print("count is \(count)")

7. 声明隐式解包选项

var mynumber: Int!
mynumber = 42
mynumber = mynumber + 1

8. 使用逻辑运算符检查多个条件

var mynumber = 42
if mynumber > 0 && mynumber < 100 {
    print("The number is between 0 and 100")
}

9. 用开关检查条件

var age = 19
var mssage = ""
switch age {
    case 0...2:
        message = "Infant"
    case 3...12:
        message = "Child"
    case 13...19:
        message = "Teenager"
    case 20...39:
        message = "Adult"
    default:
        message = "Elderly"
}

10. 使用 while 创建循环

var counter =  0 
while counter <  5 { 
    print ( "counter is \(counter) " ) 
    counter = counter +  1
 }

这些只是 Swift 的基础知识。还有很多东西需要探索和学习。快乐编码！

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