获取两个日期之间的差异

Question

I need the difference between milliseconds and the date at the moment. It needs to be formatted as HH:mm:ss and my code is not coming out with the correct difference.

var differenceDate = NSDate(timeIntervalSince1970: Double(currentTimeInMiliseconds()))
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "HH:mm:ss"
        self.callDetail.text = dateFormatter.string(from: differenceDate as Date)

 func currentTimeInMiliseconds() -> Int! {
        let date = NSDate()
        return Int(date.timeIntervalSince1970 * 1000)
    }

Answer 1

If you want the amount of time between two date objects in a HH:mm:ss format, you generally would use NSDateComponentsFormatter . In Swift 3:

let formatter = DateComponentsFormatter()
formatter.unitsStyle = .positional
formatter.allowedUnits = [.hour, .minute, .second]
formatter.zeroFormattingBehavior = .pad

let string = formatter.string(from: referenceDate, to: date)

In Swift 2:

let formatter = NSDateComponentsFormatter()
formatter.unitsStyle = .Positional
formatter.allowedUnits = [.Hour, .Minute, .Second]
formatter.zeroFormattingBehavior = .Pad

let string = formatter.stringFromDate(referenceDate, toDate: date)

Answer 2

The problem is that differenceDate , despite the name, is not a date! It's just a time interval — an abstract number of seconds. If you want to express it as hours and minutes and seconds, just keep dividing by 60 and taking the remainder. But bear in mind that those are not real hours and minutes and seconds.

Example:

// make two dates, get the difference
let greg = Calendar(identifier: .gregorian)
let dc = DateComponents(calendar: greg, 
    year: 1954, month: 8, day: 10, hour: 3, minute: 0, second: 0)
let d1 = greg.date(from: dc)!
let d2 = Date()
let diff = d2.timeIntervalSince(d1)

// calculate hours, minutes, and seconds
var min = diff/60
let sec = diff.truncatingRemainder(dividingBy: 60)
let hr = min/60
min = min.truncatingRemainder(dividingBy: 60)

// format the output as a string
let nf = NumberFormatter()
nf.roundingMode = .floor
nf.minimumIntegerDigits = 2

let hrs = nf.string(from: hr as NSNumber)
let mins = nf.string(from: min as NSNumber)

nf.maximumFractionDigits = 3
let secs = nf.string(from: sec as NSNumber)

print(hrs! + ":" + mins! + ":" + secs!) // 545169:33:18.841

This gives you your desired formatting and your milliseconds. You can do the same thing with DateComponentsFormatter, as suggested by Rob, but you'll get exactly the same calculated result.

Answer 3

I found that the easiest way was to use NSCalendar

let calendar: NSCalendar = NSCalendar.current as NSCalendar
        let date1 = call!.startTime.dateFromMilliseconds()
        let date2 = NSDate()
        let components = calendar.components([.hour, .second, .minute], from: date1 , to: date2 as Date, options: [])
        differenceDate =  NSCalendar(identifier: NSCalendar.Identifier.gregorian)?.date(from: components) as NSDate!