"Time ago" function for Swift (based on MatthewYork's DateTools for Objective-C)

timeago.swift

func timeAgoSinceDate(date:NSDate, numericDates:Bool) -> String {
    let calendar = NSCalendar.currentCalendar()
    let unitFlags = NSCalendarUnit.CalendarUnitMinute | NSCalendarUnit.CalendarUnitHour | NSCalendarUnit.CalendarUnitDay | NSCalendarUnit.CalendarUnitWeekOfYear | NSCalendarUnit.CalendarUnitMonth | NSCalendarUnit.CalendarUnitYear | NSCalendarUnit.CalendarUnitSecond
    let now = NSDate()
    let earliest = now.earlierDate(date)
    let latest = (earliest == now) ? date : now
    let components:NSDateComponents = calendar.components(unitFlags, fromDate: earliest, toDate: latest, options: nil)
    
    if (components.year >= 2) {
        return "\(components.year) years ago"
    } else if (components.year >= 1){
        if (numericDates){
            return "1 year ago"
        } else {
            return "Last year"
        }
    } else if (components.month >= 2) {
        return "\(components.month) months ago"
    } else if (components.month >= 1){
        if (numericDates){
            return "1 month ago"
        } else {
            return "Last month"
        }
    } else if (components.weekOfYear >= 2) {
        return "\(components.weekOfYear) weeks ago"
    } else if (components.weekOfYear >= 1){
        if (numericDates){
            return "1 week ago"
        } else {
            return "Last week"
        }
    } else if (components.day >= 2) {
        return "\(components.day) days ago"
    } else if (components.day >= 1){
        if (numericDates){
            return "1 day ago"
        } else {
            return "Yesterday"
        }
    } else if (components.hour >= 2) {
        return "\(components.hour) hours ago"
    } else if (components.hour >= 1){
        if (numericDates){
            return "1 hour ago"
        } else {
            return "An hour ago"
        }
    } else if (components.minute >= 2) {
        return "\(components.minute) minutes ago"
    } else if (components.minute >= 1){
        if (numericDates){
            return "1 minute ago"
        } else {
            return "A minute ago"
        }
    } else if (components.second >= 3) {
        return "\(components.second) seconds ago"
    } else {
        return "Just now"
    }
    
}

Golden. Thanks for the time saver.

If anyone found themselves here and needed usage:

if let timeAgo = timeAgoSinceDate(yourInfoAsDateFormat) {
                    
                   yourLabel.text = timeAgo
                    
                }

Here's a another version

import Foundation

extension Date {
  fileprivate struct Item {
    let multi: String
    let single: String
    let last: String
    let value: Int?
  }

  fileprivate var components: DateComponents {
    return Calendar.current.dateComponents(
      [.minute, .hour, .day, .weekOfYear, .month, .year, .second],
      from: Calendar.current.date(byAdding: .second, value: -1, to: Date())!,
      to: self
    )
  }

  fileprivate var items: [Item] {
    return [
      Item(multi: "years ago", single: "1 year ago", last: "Last year", value: components.year),
      Item(multi: "months ago", single: "1 month ago", last: "Last month", value: components.month),
      Item(multi: "weeks ago", single: "1 week ago", last: "Last week", value: components.weekday),
      Item(multi: "days ago", single: "1 day ago", last: "Last day", value: components.day),
      Item(multi: "minutes ago", single: "1 minute ago", last: "Last minute", value: components.minute),
      Item(multi: "seconds ago", single: "Just now", last: "Last second", value: components.second)
    ]
  }

  public func timeAgo(numericDates: Bool = false) -> String {
    for item in items {
      switch (item.value, numericDates) {
      case let (.some(step), _) where step == 0:
        continue
      case let (.some(step), true) where step == 1:
        return item.last
      case let (.some(step), false) where step == 1:
        return item.single
      case let (.some(step), _):
        return String(step) + " " + item.multi
      default:
        continue
      }
    }

    return "Just now"
  }
}

print(Calendar.current.date(byAdding: .day, value: 1, to: Date())!.timeAgo())

A Swift 4 version without force unwrapping:

extension Date {
    func timeAgoSinceDate(numericDates:Bool) -> String {
        let calendar = Calendar.current
        let now = Date()
        let earliest = self < now ? self : now
        let latest =  self > now ? self : now
        
        let unitFlags: Set<Calendar.Component> = [.minute, .hour, .day, .weekOfMonth, .month, .year, .second]
        let components: DateComponents = calendar.dateComponents(unitFlags, from: earliest, to: latest)
        
        if let year = components.year {
            if (year >= 2) {
                return "\(year) years ago"
            } else if (year >= 1) {
                return stringToReturn(flag: numericDates, strings: ("1 year ago", "Last year"))
            }
        }
        
        if let month = components.month {
            if (month >= 2) {
                return "\(month) months ago"
            } else if (month >= 2) {
                return stringToReturn(flag: numericDates, strings: ("1 month ago", "Last month"))
            }
        }
        
        if let weekOfYear = components.weekOfYear {
            if (weekOfYear >= 2) {
                return "\(weekOfYear) months ago"
            } else if (weekOfYear >= 2) {
                return stringToReturn(flag: numericDates, strings: ("1 week ago", "Last week"))
            }
        }
        
        if let day = components.day {
            if (day >= 2) {
                return "\(day) days ago"
            } else if (day >= 2) {
                return stringToReturn(flag: numericDates, strings: ("1 day ago", "Yesterday"))
            }
        }
        
        if let hour = components.hour {
            if (hour >= 2) {
                return "\(hour) hours ago"
            } else if (hour >= 2) {
                return stringToReturn(flag: numericDates, strings: ("1 hour ago", "An hour ago"))
            }
        }
        
        if let minute = components.minute {
            if (minute >= 2) {
                return "\(minute) minutes ago"
            } else if (minute >= 2) {
                return stringToReturn(flag: numericDates, strings: ("1 minute ago", "A minute ago"))
            }
        }
        
        if let second = components.second {
            if (second >= 3) {
                return "\(second) seconds ago"
            }
        }
        
        return "Just now"
    }
    
    private func stringToReturn(flag:Bool, strings: (String, String)) -> String {
        if (flag){
            return strings.0
        } else {
            return strings.1
        }
    }
}

Sorry for interrupting the party, but seems like "time ago" feature is implemented in DateTools with locales and just works:
https://github.com/MatthewYork/DateTools#time-ago

let timeAgoDate = 2.days.earlier
print("Time Ago: ", timeAgoDate.timeAgoSinceNow)
print("Time Ago: ", timeAgoDate.shortTimeAgoSinceNow)

//Output:
//Time Ago: 2 days ago
//Time Ago: 2d

The framework looks nice. However, sometimes only a feature is needed, not the whole framework = why to buy the whole cow if you need only milk.

This is my version. It is based on @dariukas, but fixes some bugs

import Foundation

extension Date {
    ///
    /// Provides a humanised date. For instance: 1 minute, 1 week ago, 3 months ago
    ///
    /// - Parameters:
    //      - numericDates: Set it to true to get "1 year ago", "1 month ago" or false if you prefer "Last year", "Last month"
    ///
    func timeAgo(numericDates:Bool) -> String {
        let calendar = Calendar.current
        let now = Date()
        let earliest = self < now ? self : now
        let latest =  self > now ? self : now
        
        let unitFlags: Set<Calendar.Component> = [.minute, .hour, .day, .weekOfMonth, .month, .year, .second]
        let components: DateComponents = calendar.dateComponents(unitFlags, from: earliest, to: latest)
        //print("")
        //print(components)
        if let year = components.year {
            if (year >= 2) {
                return "\(year) years ago"
            } else if (year >= 1) {
                return numericDates ?  "1 year ago" : "Last year"
            }
        }
        if let month = components.month {
            if (month >= 2) {
                return "\(month) months ago"
            } else if (month >= 1) {
                return numericDates ? "1 month ago" : "Last month"
            }
        }
        if let weekOfMonth = components.weekOfMonth {
            if (weekOfMonth >= 2) {
                return "\(weekOfMonth) weeks ago"
            } else if (weekOfMonth >= 1) {
                return numericDates ? "1 week ago" : "Last week"
            }
        }
        if let day = components.day {
            if (day >= 2) {
                return "\(day) days ago"
            } else if (day >= 1) {
                return numericDates ? "1 day ago" : "Yesterday"
            }
        }
        if let hour = components.hour {
            if (hour >= 2) {
                return "\(hour) hours ago"
            } else if (hour >= 1) {
                return numericDates ? "1 hour ago" : "An hour ago"
            }
        }
        if let minute = components.minute {
            if (minute >= 2) {
                return "\(minute) minutes ago"
            } else if (minute >= 1) {
                return numericDates ? "1 minute ago" : "A minute ago"
            }
        }
        if let second = components.second {
            if (second >= 3) {
                return "\(second) seconds ago"
            }
        }
        return "Just now"
    }
}

@merlos nice, thank you !

@merlos awesome! thank you

My version in Swift 4.2:

import Foundation

extension Date {
    func timeAgo(numericDates: Bool) -> String {
        let calendar = Calendar.current
        let now = Date()
        let earliest = self < now ? self : now
        let latest =  self > now ? self : now

        let unitFlags: Set<Calendar.Component> = [.minute, .hour, .day, .weekOfMonth, .month, .year, .second]
        let components: DateComponents = calendar.dateComponents(unitFlags, from: earliest, to: latest)

        let year = components.year ?? 0
        let month = components.month ?? 0
        let weekOfMonth = components.weekOfMonth ?? 0
        let day = components.day ?? 0
        let hour = components.hour ?? 0
        let minute = components.minute ?? 0
        let second = components.second ?? 0

        switch (year, month, weekOfMonth, day, hour, minute, second) {
            case (let year, _, _, _, _, _, _) where year >= 2: return "\(year) years ago"
            case (let year, _, _, _, _, _, _) where year == 1 && numericDates: return "1 year ago"
            case (let year, _, _, _, _, _, _) where year == 1 && !numericDates: return "Last year"
            case (_, let month, _, _, _, _, _) where month >= 2: return "\(month) months ago"
            case (_, let month, _, _, _, _, _) where month == 1 && numericDates: return "1 month ago"
            case (_, let month, _, _, _, _, _) where month == 1 && !numericDates: return "Last month"
            case (_, _, let weekOfMonth, _, _, _, _) where weekOfMonth >= 2: return "\(weekOfMonth) weeks ago"
            case (_, _, let weekOfMonth, _, _, _, _) where weekOfMonth == 1 && numericDates: return "1 week ago"
            case (_, _, let weekOfMonth, _, _, _, _) where weekOfMonth == 1 && !numericDates: return "Last week"
            case (_, _, _, let day, _, _, _) where day >= 2: return "\(day) days ago"
            case (_, _, _, let day, _, _, _) where day == 1 && numericDates: return "1 day ago"
            case (_, _, _, let day, _, _, _) where day == 1 && !numericDates: return "Yesterday"
            case (_, _, _, _, let hour, _, _) where hour >= 2: return "\(hour) hours ago"
            case (_, _, _, _, let hour, _, _) where hour == 1 && numericDates: return "1 hour ago"
            case (_, _, _, _, let hour, _, _) where hour == 1 && !numericDates: return "An hour ago"
            case (_, _, _, _, _, let minute, _) where minute >= 2: return "\(minute) minutes ago"
            case (_, _, _, _, _, let minute, _) where minute == 1 && numericDates: return "1 minute ago"
            case (_, _, _, _, _, let minute, _) where minute == 1 && !numericDates: return "A minute ago"
            case (_, _, _, _, _, _, let second) where second >= 3: return "\(second) seconds ago"
            default: return "Just now"
        }
    }
}