Xcode 上午/下午时间到24小时格式

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最佳答案

Just convert it to a date using NSDateFormatter and the "h:mm a" format and convert it back to a string using the "HH:mm" format. Check out this date formatting guide to familiarize yourself with this material.

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!)

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I am using a function here in my case by which I am updating a label with the normal time format and after that I am storing the selected time's 24hr format to do some another tasks..

Here is my code...

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.
}

After writing this function you can call this where you are choosing the time from date/time picker.

Thanks, Hope this helped.

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Here is code for other way around

For 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
}

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Swift 3

Time format 24 hours to 12 hours

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)

output will be 12 hour formatted Date: 1:15 PM

Time format 12 hours to 24 hours

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)

output will be 24 hour formatted Date: 13:15

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Below is the swift 3 version of the solution -

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)

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Swift version 3.0.2 , Xcode Version 8.2.1 (8C1002) (12 hr format ):

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
}

OUTPUT : 12:41:42 AM

Feel free to comment. Thanks

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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())

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Swift 3 *

Code to convert 12 hours (i.e. AM and PM) to 24 hours format which includes-

Hours:Minutes:Seconds:AM/PM to Hours:Minutes:Seconds

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
}

Input

07:05:45PM

Output

19:05:45

Similarly

Code to convert 24 hours to 12 hours (i.e. AM and PM) format which includes-

Hours:Minutes:Seconds to Hours:Minutes:Seconds: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
}

Input

19:05:45

Output

07:05:45PM

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Unfortunately apple priority the device date format, so in some cases against what you put, swift change your format to 12hrs

To fix this is necessary to use setLocalizedDateFormatFromTemplate instead of dateFormat an hide the AM and 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())

You can check a very useful post with more information detailed in https://prograils.com/posts/the-curious-case-of-the-24-hour-time-format-in-swift

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Use this function for date conversion, its working fine when your device in 24/12 hr format

See 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!) : ""
}

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Here is the answer with more extra format.

** 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)

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this is similar to our friends answer: https://stackoverflow.com/a/43801717/2796837 but using all our internet friends ideas I came up with the following more complete singular solution:

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)
}

This will parse your time even independent of the format it comes and outputs it into HH:mm, you could change the third format change into whatever you would want.