xcode swift am/pm time to 24 hour format

问题:

I am trying to convert a am/pm format time to a 24 hour format time

6:35 PM to 18:35

I tried this piece of code on playground but it doesnt seem to work if I put the time alone

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

Does anyone know how to accomplish this?

Thank you.

回答1:

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"
let date = dateFormatter.dateFromString(dateAsString)

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

回答2:

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

回答3:

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)

回答4:

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
}

回答5:

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

回答6:

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.