Time Ago String Swift 3

Date+Extension.swift

    
  extension: Date {
  
    var timeAgoString: String {
        let interval = Calendar.current.dateComponents([.year, .month, .day, .hour], from: self, to: Date())
        if let year = interval.year, year > 0 {
            return year == 1 ? "\(year) year ago" : "\(year) years ago"
        } else if let month = interval.month, month > 0 {
            return month == 1 ? "\(month) month ago" : "\(month) months ago"
        } else if let day = interval.day, day > 0 {
            return day == 1 ? "\(day) day ago" : "\(day) days ago"
        } else if let hour = interval.hour, hour > 0 {
            return hour == 1 ? "\(hour) hour ago" : "\(hour) hours ago"
        } else {
            return "a moment ago"
        }
    }
    
 }