Search code examples
swiftdatefoundationdateformatterdateinterval

DateIntervalFormatter: string of format "m:ss"

I'd like to get a string of format "m:ss" out of two dates. E.g.: "0:27" for 27 seconds difference and "1:30" for 90 seconds difference between dates.

Here's the code I'm using:

import Foundation
let formatter = DateIntervalFormatter()
formatter.dateStyle = .none
formatter.timeStyle = .none
formatter.dateTemplate = "m:ss"

let startDate = Date()
let endDate = Date(timeInterval: 1, since: startDate)

let outputString = formatter.string(from: startDate, to: endDate)
print(outputString) //16:12 – 16:13 ???
// This is correct, but it doesn't actually calculate the interval.

But I'm getting just two dates printed out with a dash. How can I actually make the DateIntervalFormatter to calculate the difference as I want?

The code is almost 1:1 sample from the Apple documentation but with the custom dateTemplate: https://developer.apple.com/documentation/foundation/dateintervalformatter

Solution

  • It seems that you actually want DateComponentsFormatter

    let formatter = DateComponentsFormatter()
formatter.allowedUnits = [.minute, .second]
formatter.zeroFormattingBehavior = .pad
let startDate = Date()
let endDate = Date(timeInterval: 129, since: startDate)

let outputString = formatter.string(from: startDate, to: endDate)!
print(outputString)

    to remove the leading zero if the minutes are < 10 you could use Regular Expression

    print(outputString.replacingOccurrences(of: "^0(\\d)", with: "$1", options: .regularExpression))