问题描述
我试图打印出星期几的名称，即星期一，星期二，星期三。我目前有这样的代码就是这样做的。我想知道是否有办法摆脱我的switch语句并使其更好。谢谢！
Im trying to print out the name of the day of the week i.e Monday, Tuesday, Wednesday. I currently have this bit of code that does just that. I was wondering if there is a way to get rid of my switch statement and make this better. Thanks!
func getDayOfWeek(_ today: String) -> String? {
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd"
guard let todayDate = formatter.date(from: today) else { return nil }
let myCalendar = Calendar(identifier: .gregorian)
let weekDay = myCalendar.component(.weekday, from: todayDate)
switch weekDay {
case 1:
return "Sunday"
case 2:
return "Monday"
case 3:
return "Tuesday"
case 4:
return "Wednesday"
case 5:
return "Thursday"
case 6:
return "Friday"
case 7:
return "Saturday"
default:
return ""
}
}
getDayOfWeek("2018-3-5")
打印出星期一
推荐答案
您使用的日期格式错误。正确的格式是yyyy-M-d。除此之外，你可以使用Calendar属性weekdaySymbols返回工作日本地化。
You are using the wrong date format. The correct format is "yyyy-M-d". Besides that you can use Calendar property weekdaySymbols which returns the weekday localized.
func getDayOfWeek(_ date: String) -> String? {
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-M-d"
formatter.locale = Locale(identifier: "en_US_POSIX")
guard let todayDate = formatter.date(from: date) else { return nil }
let weekday = Calendar(identifier: .gregorian).component(.weekday, from: todayDate)
return Calendar.current.weekdaySymbols[weekday-1] // "Monday"
}
另一种选择是使用DateFormatter并将dateFormat设置为cccc，您可以在此中看到：
Another option is to use DateFormatter and set your dateFormat to "cccc" as you can see in this answer:
extension Formatter {
static let weekdayName: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "cccc"
return formatter
}()
static let customDate: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-M-d"
formatter.locale = Locale(identifier: "en_US_POSIX")
return formatter
}()
}
extension Date {
var weekdayName: String {
return Formatter.weekdayName.string(from: self)
}
}
使用上面的扩展程序如下所示：
Using the extension above your function would look like this:
func getDayOfWeek(_ date: String) -> String? {
return Formatter.customDate.date(from: date)?.weekdayName
}
游乐场测试：
getDayOfWeek("2018-3-5") // Monday
Date().weekdayName // Thursday
这篇关于如何打印星期几的名称？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！