App Crashed when device time is in 24 hour format

问题

In my App if IPhone device time is in 12 hour formate then date formatter works correctly but if device time is in 24 hour formate then app crashed.

 let dateFormatter = NSDateFormatter();
 dateFormatter.dateStyle = NSDateFormatterStyle.ShortStyle
 dateFormatter.timeStyle = NSDateFormatterStyle.NoStyle;
 dateFormatter.dateFormat = "hh:mm a";
 var dt1 = dateFormatter.dateFromString(arrSecond.objectAtIndex(n) as! String)

回答1:

@Rajan Thanks for giving me idea of NSLocale. I set the dateformatter's locale identifier to "en_US_POSIX". i just add this below line in my code after allocating date formatter. dateformatter.locale = NSLocale(localeIdentifier:"en_US_POSIX") Thanks frnd for giving this idea

回答2:

Nandini answer is correct. But the only issue is that if you harcode the locale, the dates are displayed only in english.

In my case I wanted it in french, here is a workaround that worked for me in Swift 3 :

dateformatter.locale = Locale(identifier: NSLocale.current.identifier)

回答3:

Assuming that you are using Swift 2.x version after seeing your code.

The problem is because your dateFormatter contains a and for the 24 Hour Format time we don't have a

So in order to fix your problem, you have to check whether your device is in 24-Hour format or 12 Hour format

Taking your array's index object in a variable time and keep that as var because we will change that later.

var time = arrSecond.objectAtIndex(n) as! String //this contains 07:45 AM

//Now create your Date Formatter
let dateFormatter = NSDateFormatter();
dateFormatter.dateStyle = NSDateFormatterStyle.ShortStyle
dateFormatter.timeStyle = NSDateFormatterStyle.NoStyle;

//Now check whether your phone is in 12 hour or 24 hour format 
let locale = NSLocale.currentLocale()
let formatter : String = NSDateFormatter.dateFormatFromTemplate("j", options:0, locale:locale)!

//we have to change our dateFormatter as per the hour format
if formatter.containsString("a") {
    print("phone is in 12 Hour Format")
    dateFormatter.dateFormat = "hh:mm a";
} else {
    print("phone is in 24 Hour Format")
    time = convertTo24HourFormat(time) //time changed to 24 Hour format and AM/PM removed from string
    dateFormatter.dateFormat = "HH:mm";
}

let finalDate = dateFormatter.dateFromString(time)
print(finalDate!)

And we need a function to make your time string converted to 24 hour format if your phone is in 24 Hour Format.
Function defination of convertTo24HourFormat is

//Example 08:45 PM to 20:45
func convertTo24HourFormat(time:String) -> String {
    var formattedTime = time
    if formattedTime.containsString("PM") {
        var hour = Int(formattedTime.substringToIndex(formattedTime.startIndex.advancedBy(2)))
        if hour != 12 {
            hour = hour! + 12
            formattedTime.removeRange(Range<String.Index>(start: formattedTime.startIndex, end: formattedTime.startIndex.advancedBy(2)))
            formattedTime = "\(hour!)\(formattedTime)"
        }

    } else {
        // For AM time
        var hour = Int(formattedTime.substringToIndex(formattedTime.startIndex.advancedBy(2)))

        //case for 12 AM
        if hour == 12 {
            formattedTime.removeRange(Range<String.Index>(start: formattedTime.startIndex, end: formattedTime.startIndex.advancedBy(2)))
            formattedTime = "00\(formattedTime)"
        }
    }
    formattedTime = formattedTime.substringToIndex(time.startIndex.advancedBy(5))

    return formattedTime
}

But converting only the time to date object don't make any sense as it will give a wrong date.

NOTE:-
The convertTo24HourFormat function will only work fine if you send the time in the format hh:mm a. For example 07:45 AM

回答4:

I had to change my formatter from this:

dateFormatter.dateFormat = "dd MM yyyy hh:mm:ss.SSS"

to this:

dateFormatter.dateFormat = "dd MM yyyy HH:mm:ss.SSS"

来源：https://stackoverflow.com/questions/40055740/app-crashed-when-device-time-is-in-24-hour-format

标签

swift

nsdate

nsdateformatter