Time ago/ahead in Swift

DateHelpers.swift

import Foundation

struct DateComponentUnitFormatter {
    
    private struct DateComponentUnitFormat {
        let unit: Calendar.Component
        
        let singularUnit: String
        let pluralUnit: String
        
        let futureSingular: String
        let pastSingular: String
    }
    
    private let formats: [DateComponentUnitFormat] = [
        
        DateComponentUnitFormat(unit: .year,
                                singularUnit: "year",
                                pluralUnit: "years",
                                futureSingular: "Next year",
                                pastSingular: "Last year"),
        
        DateComponentUnitFormat(unit: .month,
                                singularUnit: "month",
                                pluralUnit: "months",
                                futureSingular: "Next month",
                                pastSingular: "Last month"),
        
        DateComponentUnitFormat(unit: .weekOfYear,
                                singularUnit: "week",
                                pluralUnit: "weeks",
                                futureSingular: "Next week",
                                pastSingular: "Last week"),
        
        DateComponentUnitFormat(unit: .day,
                                singularUnit: "day",
                                pluralUnit: "days",
                                futureSingular: "Tomorrow",
                                pastSingular: "Yesterday"),
        
        DateComponentUnitFormat(unit: .hour,
                                singularUnit: "hour",
                                pluralUnit: "hours",
                                futureSingular: "In an hour",
                                pastSingular: "An hour ago"),
        
        DateComponentUnitFormat(unit: .minute,
                                singularUnit: "minute",
                                pluralUnit: "minutes",
                                futureSingular: "In a minute",
                                pastSingular: "A minute ago"),
        
        DateComponentUnitFormat(unit: .second,
                                singularUnit: "second",
                                pluralUnit: "seconds",
                                futureSingular: "Just now",
                                pastSingular: "Just now"),
        
        ]
    
    func string(forDateComponents dateComponents: DateComponents, useNumericDates: Bool) -> String {
        for format in self.formats {
            let unitValue: Int
            
            switch format.unit {
            case .year:
                unitValue = dateComponents.year ?? 0
            case .month:
                unitValue = dateComponents.month ?? 0
            case .weekOfYear:
                unitValue = dateComponents.weekOfYear ?? 0
            case .day:
                unitValue = dateComponents.day ?? 0
            case .hour:
                unitValue = dateComponents.hour ?? 0
            case .minute:
                unitValue = dateComponents.minute ?? 0
            case .second:
                unitValue = dateComponents.second ?? 0
            default:
                assertionFailure("Date does not have requried components")
                return ""
            }
            
            switch unitValue {
            case 2 ..< Int.max:
                return "\(unitValue) \(format.pluralUnit) ago"
            case 1:
                return useNumericDates ? "\(unitValue) \(format.singularUnit) ago" : format.pastSingular
            case -1:
                return useNumericDates ? "In \(-unitValue) \(format.singularUnit)" : format.futureSingular
            case Int.min ..< -1:
                return "In \(-unitValue) \(format.pluralUnit)"
            default:
                break
            }
        }
        
        return "Just now"
    }
}

extension Date {
    
    func timeAgoSinceNow(useNumericDates: Bool = false) -> String {
        
        let calendar = Calendar.current
        let unitFlags: Set<Calendar.Component> = [.minute, .hour, .day, .weekOfYear, .month, .year, .second]
        let now = Date()
        let components = calendar.dateComponents(unitFlags, from: self, to: now)
        
        let formatter = DateComponentUnitFormatter()
        return formatter.string(forDateComponents: components, useNumericDates: useNumericDates)
    }
}

you just saved me an hour thanks

Awesome!

I've made some changes to conform to my project's needs, referencing your work. Check it out: https://gist.github.com/ckalbas/eccdc7db6893001d0811dea7823549a2

Great job, thanks!

Thanks!!!! Awesome job!

I want to get the new string according to the currentTimeZone?
For example : My date is 2019-08-20 21:50:00 UTC
I am in IST
I get "Tomorrow"
But i need to get it according to IST which should be day after tomorrow

Sounds like your date might be deserializing incorrectly? If you convert it to a string using DateFormatter, is it in the correct time zone?

Sounds like your date might be deserializing incorrectly? If you convert it to a string using DateFormatter, is it in the correct time zone?

No, my serailizing is fine. But the relative time that is being returned is according to UTC which is not my timezone

That doesn't make sense. There's no presumption of time zone in this code and Date is time zone independent ("A specific point in time, independent of any calendar or time zone." - Apple Docs).