Swift - 39 - 枚举类型关联默认值

Posted 2020-06-12

//: Playground - noun: a place where people can play

import UIKit

enum Month: Int
{
    // 这么定义, 后面的Feb, Mar会自动赋值为2和3..
    case Jan = 1, Feb, Mar, Apr, May, Jun, July, Aug, Sep, Oct, Nov, Dec
}

let currentMonth:Month = .Nov
// 查看枚举对应的值
currentMonth.rawValue

// 通过这种方法创建出来的枚举变量是一个可选型变量..需要解包后使用
let nextMonth = Month(rawValue: 12)
nextMonth!.rawValue

// 示例
var userInputNumber = 0
if let theMonth = Month(rawValue: userInputNumber) {
    switch theMonth {
    case .Jan:
        print("It‘s the first month")
    case .Dec:
        print("It‘s the last month")
    default:
        print("It‘s the normal month")
    }
} else {
    print("ERROR")
}

// swift中关联的默认值不仅仅是整数, 也可以字符串等其他类型
enum PersonNum: String
{
    case one = "Rinpe"
    case two = "Lili"
    case three = "Lolo"
}

// 示例
let userInput = "Rinpe"
if PersonNum(rawValue: userInput) != nil {
    print("欢迎您, \(userInput)教授")
} else {
    print("对不起, 您不是本公司的员工")
}