上午/下午时间改为 24 小时格式

Question

我正在尝试将 am/pm 格式时间转换为 24 小时格式时间

6:35 PM to 18:35

我在操场上尝试了这段代码，但似乎没有 如果我有时间独自工作

let dateAsString = "02/12/15, 6:35 PM"
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "HH"
let date = dateFormatter.dateFromString(dateAsString) //returns nil

有谁知道如何做到这一点？

Answer 1

只需使用 NSDateFormatter 和“h:mm a”格式将其转换为日期，然后使用“HH:mm”格式将其转换回字符串。查看此日期格式指南以熟悉此材料。

let dateAsString = "6:35 PM"
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "h:mm a"
dateFormatter.locale = Locale(identifier: "en_US_POSIX") // fixes nil if device time in 24 hour format
let date = dateFormatter.dateFromString(dateAsString)

dateFormatter.dateFormat = "HH:mm"
let date24 = dateFormatter.stringFromDate(date!)

Answer 2

斯威夫特3

时间格式24小时到12小时

let dateAsString = "13:15"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm"

let date = dateFormatter.date(from: dateAsString)
dateFormatter.dateFormat = "h:mm a"
let Date12 = dateFormatter.string(from: date!)
print("12 hour formatted Date:",Date12)

输出将为 12 小时格式日期：下午 1:15

时间格式12小时到24小时

let dateAsString = "1:15 PM"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "h:mm a"

let date = dateFormatter.date(from: dateAsString)
dateFormatter.dateFormat = "HH:mm"

let Date24 = dateFormatter.string(from: date!)
print("24 hour formatted Date:",Date24)

输出将为 24 小时格式日期：13:15

Answer 3

斯威夫特 3 *

将 12 小时（即上午和下午）转换为 24 小时格式的代码，其中包括 -

时:分:秒:AM/PM 至时:分:秒

func timeConversion24(time12: String) -> String {
    let dateAsString = time12
    let df = DateFormatter()
    df.dateFormat = "hh:mm:ssa"

    let date = df.date(from: dateAsString)
    df.dateFormat = "HH:mm:ss"

    let time24 = df.string(from: date!)
    print(time24)
    return time24
}

输入

07:05:45PM

输出

19:05:45

同样

将 24 小时转换为 12 小时（即 AM 和 PM） 格式的代码，其中包括 -

小时:分钟:秒到小时:分钟:秒:AM/PM

func timeConversion12(time24: String) -> String {
    let dateAsString = time24
    let df = DateFormatter()
    df.dateFormat = "HH:mm:ss"

    let date = df.date(from: dateAsString)
    df.dateFormat = "hh:mm:ssa"

    let time12 = df.string(from: date!)
    print(time12)
    return time12
}

输入

19:05:45

输出

07:05:45PM

Answer 4

这是带有更多额外格式的答案。

** Xcode 12、Swift 5.3 **

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm:ss"
var dateFromStr = dateFormatter.date(from: "12:16:45")!

dateFormatter.dateFormat = "hh:mm:ss a 'on' MMMM dd, yyyy"
//Output: 12:16:45 PM on January 01, 2000

dateFormatter.dateFormat = "E, d MMM yyyy HH:mm:ss Z"
//Output: Sat, 1 Jan 2000 12:16:45 +0600

dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
//Output: 2000-01-01T12:16:45+0600

dateFormatter.dateFormat = "EEEE, MMM d, yyyy"
//Output: Saturday, Jan 1, 2000

dateFormatter.dateFormat = "MM-dd-yyyy HH:mm"
//Output: 01-01-2000 12:16

dateFormatter.dateFormat = "MMM d, h:mm a"
//Output: Jan 1, 12:16 PM

dateFormatter.dateFormat = "HH:mm:ss.SSS"
//Output: 12:16:45.000

dateFormatter.dateFormat = "MMM d, yyyy"
//Output: Jan 1, 2000

dateFormatter.dateFormat = "MM/dd/yyyy"
//Output: 01/01/2000

dateFormatter.dateFormat = "hh:mm:ss a"
//Output: 12:16:45 PM

dateFormatter.dateFormat = "MMMM yyyy"
//Output: January 2000

dateFormatter.dateFormat = "dd.MM.yy"
//Output: 01.01.00

//Output: Customisable AP/PM symbols
dateFormatter.amSymbol = "am"
dateFormatter.pmSymbol = "Pm"
dateFormatter.dateFormat = "a"
//Output: Pm

// Usage
var timeFromDate = dateFormatter.string(from: dateFromStr)
print(timeFromDate)

Answer 5

下面是 swift 3 版本的解决方案 -

let dateAsString = "6:35:58 PM"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "h:mm:ss a"
let date = dateFormatter.date(from: dateAsString)

dateFormatter.dateFormat = "HH:mm:ss"
let date24 = dateFormatter.string(from: date!)
print(date24)

Answer 6

Swift 版本 3.0.2，Xcode 版本 8.2.1 (8C1002)（12 小时格式）：

func getTodayString() -> String{

        let formatter = DateFormatter()
        formatter.dateFormat = "h:mm:ss a "
        formatter.amSymbol = "AM"
        formatter.pmSymbol = "PM"

        let currentDateStr = formatter.string(from: Date())
        print(currentDateStr)
        return currentDateStr 
}

输出： 12:41:42 AM

欢迎评论。谢谢

Answer 7

使用此功能进行日期转换，当您的设备采用 24/12 小时格式时，它工作正常

参见https://developer.apple.com/library/archive/qa/qa1480/_index.html

func convertDateFormatter(fromFormat:String,toFormat:String,_ dateString: String) -> String{
    let formatter = DateFormatter()
    formatter.locale = Locale(identifier: "en_US_POSIX")
    formatter.dateFormat = fromFormat
    let date = formatter.date(from: dateString)
    formatter.dateFormat = toFormat
    return  date != nil ? formatter.string(from: date!) : ""
}

Answer 8

不幸的是，苹果优先考虑设备日期格式，因此在某些情况下，根据您输入的内容，迅速将格式更改为 12 小时

要解决此问题，需要使用 setLocalizedDateFormatFromTemplate 而不是 dateFormat 并隐藏 AM 和 PM

let formatter = DateFormatter()
formatter.setLocalizedDateFormatFromTemplate("HH:mm:ss a")
formatter.amSymbol = ""
formatter.pmSymbol = ""
formatter.timeZone = TimeZone(secondsFromGMT: 0)
var prettyDate = formatter.string(from: Date())

您可以查看一篇非常有用的帖子，其中详细介绍了更多信息 https://prograils.com/posts/the-curious-case-of-the-24-hour-time-format-in-swift

Answer 9

这是其他方式的代码

对于 Swift 3

 func amAppend(str:String) -> String{
    var temp = str
    var strArr = str.characters.split{$0 == ":"}.map(String.init)
    var hour = Int(strArr[0])!
    var min = Int(strArr[1])!
    if(hour > 12){
        temp = temp + "PM"
    }
    else{
        temp = temp + "AM"
    }
    return temp
}

Answer 10

let calendar = Calendar.current
let hours    = calendar.component(.hour, from: Date())
let minutes  = calendar.component(.minute, from: Date())
let seconds  = calendar.component(.second, from: Date())

Answer 11

在我的例子中，我在这里使用一个函数，通过该函数我用正常时间格式更新标签，然后我存储所选时间的 24 小时格式以执行其他一些任务..

这是我的代码...

func timeUpdate(sender: NSDate)
{
    let timeSave = NSDateFormatter() //Creating first object to update time label as 12hr format with AM/PM
    timeSave.timeStyle = NSDateFormatterStyle.ShortStyle //Setting the style for the time selection.
    self.TimeShowOutlet.text = timeSave.stringFromDate(sender) // Getting the string from the selected time and updating the label as 1:40 PM
    let timeCheck = NSDateFormatter() //Creating another object to store time in 24hr format.
    timeCheck.dateFormat = "HH:mm:ss" //Setting the format for the time save.
    let time = timeCheck.stringFromDate(sender) //Getting the time string as 13:40:00
    self.timeSelectedForCheckAvailability = time //At last saving the 24hr format time for further task.
}

编写此函数后，您可以在从日期/时间选择器中选择时间时调用此函数。

谢谢， 希望这有帮助。

Answer 12

这与我们朋友的答案类似：https://stackoverflow.com/a/43801717/2796837但是利用我们所有互联网朋友的想法，我想出了以下更完整的单一解决方案：

let amPmFormat = "h:mm a"
let twentyFourHFormat = "HH:mm"
func hourMinuteParser(date: Date) -> KotlinInt{
    let formatter = DateFormatter()
    if DateFormatter.dateFormat(fromTemplate: "j",options:0, locale: Locale.current)!.contains("a") {
        formatter.dateFormat = amPmFormat
    }else{
        formatter.dateFormat = twentyFourHFormat
    }
    let stringTime = formatter.string(from: date)
    let time = formatter.date(from: stringTime)
    formatter.dateFormat = twentyFourHFormat

    let time24 = formatter.string(from: time!)
    let timeWithoutSpecialCharacters = time24.replacingOccurrences(of: ":", with: "")
    let int2 = Int32(timeWithoutSpecialCharacters) ?? 0
    return KotlinInt(int: int2)
}

这将解析您的时间，甚至与它的格式无关，并将其输出为 HH:mm，您可以将第三个格式更改为您想要的任何格式。

Answer 13

为了方便起见，我添加了以下字符串扩展：

import Foundation

extension String {
    // Converts 24-hour format to 12-hour format
    // Input: 22:15
    // Output: 10:15 PM
    var time12String: String {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "HH:mm"
        guard let date = dateFormatter.date(from: self) else {
            return "Invalid Time String"
        }
        dateFormatter.dateFormat = "hh:mm a"
        return dateFormatter.string(from: date)
    }
    
    // Converts 12-hour format to 24-hour format
    // Input: 10:15 PM
    // Output: 22:15
    var time24String: String {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "hh:mm a"
        guard let date = dateFormatter.date(from: self) else {
            return "Invalid Time String"
        }
        dateFormatter.dateFormat = "HH:mm"
        return dateFormatter.string(from: date)
    }
}

用途：

let timeIn12Hour = "22:15".time12String
print(timeIn12Hour)
// Output: 10:15 PM

let timeIn24Hour = "10:15 PM".time24String
print(timeIn24Hour)
// Output: 22:15

从你的问题假设你不关心这里的日期。如果您需要日期，则需要正确更新格式