ios 获取年月日是周几 星期一返回周一 星期二返回周二 星期三返回周三 星期四返回周四 星期五返回周五 星期六返回周六 星期天返回周天

可以使用 NSDateFormatter 类和 NSCalendar 类来获取年月日对应的周几。

首先，需要获取当前时间的年月日，可以使用 NSDate 类和 NSDateFormatter 类来进行格式化：

let date = Date()
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let formattedDate = dateFormatter.string(from: date)

接下来，使用 NSCalendar 类的 component(_:from:) 方法来获取当前日期对应的星期几：

let calendar = Calendar.current
let weekDay = calendar.component(.weekday, from: date)

最后，根据星期几的值来判断返回的周几字符串：

var weekDayString = ""
switch weekDay {
    case 1:
        weekDayString = "周日"
    case 2:
        weekDayString = "周一"
    case 3:
        weekDayString = "周二"
    case 4:
        weekDayString = "周三"
    case 5:
        weekDayString = "周四"
    case 6:
        weekDayString = "周五"
    case 7:
        weekDayString = "周六"
    default:
        break
}

完整的代码示例如下：

import UIKit

let date = Date()
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let formattedDate = dateFormatter.string(from: date)

let calendar = Calendar.current
let weekDay = calendar.component(.weekday, from: date)

var weekDayString = ""
switch weekDay {
    case 1:
        weekDayString = "周日"
    case 2:
        weekDayString = "周一"
    case 3:
        weekDayString = "周二"
    case 4:
        weekDayString = "周三"
    case 5:
        weekDayString = "周四"
    case 6:
        weekDayString = "周五"
    case 7:
        weekDayString = "周六"
    default:
        break
}

print("\(formattedDate) 是\(weekDayString)")

输出的结果会是当前日期对应的年月日和周几，例如："2022-07-25 是周一"