Swift 5.1•iOS 13

你可以使用苹果在iOS 13中引入的RelativeDateFormatter。

let exampleDate = Date().addingTimeInterval(-15000)

let formatter = RelativeDateTimeFormatter()
formatter.unitsStyle = .full
let relativeDate = formatter.localizedString(for: exampleDate, relativeTo: Date())

print(relativeDate) // 4 hours ago

参见如何使用RelativeDateTimeFormatter显示相对日期和时间。

如果你的目的是获得两个日期之间的确切天数，你可以这样解决这个问题:

// Assuming that firstDate and secondDate are defined
// ...

var calendar: NSCalendar = NSCalendar.currentCalendar()

// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDayForDate(firstDate)
let date2 = calendar.startOfDayForDate(secondDate)

let flags = NSCalendarUnit.DayCalendarUnit
let components = calendar.components(flags, fromDate: date1, toDate: date2, options: nil)

components.day  // This will return the number of day(s) between dates

在jose920405中添加了一些答案，使其与Swift 3.0及以上版本兼容

func getDateTimeDiff(dateStr:String) -> String {
    
    let formatter : DateFormatter = DateFormatter()
    formatter.timeZone = NSTimeZone.local
    formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
    
    let now = formatter.string(from: NSDate() as Date)
    let startDate = formatter.date(from: dateStr)
    let endDate = formatter.date(from: now)
    
    // *** create calendar object ***
    var calendar = NSCalendar.current
    
    // *** Get components using current Local & Timezone ***
    print(calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: startDate!))
    
    // *** define calendar components to use as well Timezone to UTC ***
    let unitFlags = Set<Calendar.Component>([.year, .month, .day, .hour, .minute, .second])
    calendar.timeZone = TimeZone(identifier: "UTC")!
    let dateComponents = calendar.dateComponents(unitFlags, from: startDate!, to: endDate!)
    
    // *** Get Individual components from date ***
    let years = dateComponents.year!
    let months = dateComponents.month!
    let days = dateComponents.day!
    let hours = dateComponents.hour!
    let minutes = dateComponents.minute!
    let seconds = dateComponents.second!
    
    var timeAgo = ""
    
    if (seconds > 0){
        if seconds < 2 {
            timeAgo = "Second Ago"
        }
        else{
            timeAgo = "\(seconds) Second Ago"
        }
    }
    
    if (minutes > 0){
        if minutes < 2 {
            timeAgo = "Minute Ago"
        }
        else{
            timeAgo = "\(minutes) Minutes Ago"
        }
    }
    
    if(hours > 0){
        if hours < 2 {
            timeAgo = "Hour Ago"
        }
        else{
            timeAgo = "\(hours) Hours Ago"
        }
    }
    
    if (days > 0) {
        if days < 2 {
            timeAgo = "Day Ago"
        }
        else{
            timeAgo = "\(days) Days Ago"
        }
    }
    
    if(months > 0){
        if months < 2 {
            timeAgo = "Month Ago"
        }
        else{
            timeAgo = "\(months) Months Ago"
        }
    }
    
    if(years > 0){
        if years < 2 {
            timeAgo = "Year Ago"
        }
        else{
            timeAgo = "\(years) Years Ago"
        }
    }
    
    DLog("timeAgo is ===> \(timeAgo)")
    return timeAgo;
}

我在Leo Dabus的asnwer中添加了一个“长”版本，以防你想要一个字符串，说“2周前”而不是“2w”……

extension Date {
    func offsetLong(from date: Date) -> String {
        if years(from: date) > 0 {
            return years(from: date) > 1 ? "\(years(from: date)) years ago" : "\(years(from: date)) year ago"
        }
        if months(from: date) > 0 {
            return months(from: date) > 1 ? "\(months(from: date)) months ago" : "\(months(from: date)) month ago" 
        }
        if weeks(from: date) > 0 {
            return weeks(from: date) > 1 ? "\(weeks(from: date)) weeks ago" : "\(weeks(from: date)) week ago"
        }
        if days(from: date) > 0 {
            return days(from: date) > 1 ? "\(days(from: date)) days ago" : "\(days(from: date)) day ago" 
        }
        if hours(from: date) > 0 {
            return hours(from: date) > 1 ? "\(hours(from: date)) hours ago" : "\(hours(from: date)) hour ago"
        }
        if minutes(from: date) > 0 {
            return minutes(from: date) > 1 ? "\(minutes(from: date)) minutes ago" : "\(minutes(from: date)) minute ago"
        }
        if seconds(from: date) > 0 {
            return seconds(from: date) > 1 ? "\(seconds(from: date)) seconds ago" : "\(seconds(from: date)) second ago"
        }
        return ""
    }
}

在Swift 2.2中

    /// Returns the amount of years from another date
func years(fromdate: NSDate) -> Int {
    return NSCalendar.currentCalendar().components([.Year], fromDate: fromdate, toDate: NSDate(), options: []).year ?? 0
}
/// Returns the amount of months from another date
func months(fromdate: NSDate) -> Int {
    return NSCalendar.currentCalendar().components([.Month], fromDate: fromdate, toDate: NSDate(), options: []).month ?? 0
}
/// Returns the amount of weeks from another date
func weeks(fromdate: NSDate) -> Int {
    return NSCalendar.currentCalendar().components([.WeekOfYear], fromDate: fromdate, toDate: NSDate(), options: []).weekOfYear ?? 0
}
/// Returns the amount of days from another date
func days(fromdate: NSDate) -> Int {
    return NSCalendar.currentCalendar().components([.Day], fromDate: fromdate, toDate: NSDate(), options: []).day ?? 0
}
/// Returns the amount of hours from another date
func hours(fromdate: NSDate) -> Int {
    return NSCalendar.currentCalendar().components([.Hour], fromDate: fromdate, toDate: NSDate(), options: []).hour ?? 0
}
/// Returns the amount of minutes from another date
func minutes(fromdate: NSDate) -> Int {
    return NSCalendar.currentCalendar().components([.Minute], fromDate: fromdate, toDate: NSDate(), options: []).minute ?? 0
}
/// Returns the amount of seconds from another date
func seconds(fromdate: NSDate) -> Int {
    return NSCalendar.currentCalendar().components(.Second, fromDate: fromdate, toDate: NSDate(), options: []).second ?? 0
}

斯威夫特5

func dateDiff(dateStr:String) -> String {
    let f:DateFormatter = DateFormatter()
    f.timeZone = NSTimeZone.local
      f.dateFormat = "yyyy-M-dd'T'HH:mm:ss.SSSZZZ"
      
    let now = f.string(from: NSDate() as Date)
    let startDate = f.date(from: dateStr)
    let endDate = f.date(from: now)
    var _: NSCalendar = NSCalendar.current as NSCalendar
      
    
    let dateComponents = Calendar.current.dateComponents([ .weekOfMonth, .day , .hour , .minute , .second], from: startDate!, to: endDate!)
      
      let weeks = abs(dateComponents.weekOfMonth!)
      let days = abs(dateComponents.day!)
      let hours = abs(dateComponents.hour!)
      let min = abs(dateComponents.minute!)
      let sec = abs(dateComponents.second!)
      
      var timeAgo = ""

      if (sec > 0){
          if (sec > 1) {
              timeAgo = "\(sec) Seconds Ago"
          } else {
              timeAgo = "\(sec) Second Ago"
          }
      }
      
      if (min > 0){
          if (min > 1) {
              timeAgo = "\(min) Minutes Ago"
          } else {
              timeAgo = "\(min) Minute Ago"
          }
      }
      
      if(hours > 0){
          if (hours > 1) {
              timeAgo = "\(hours) Hours Ago"
          } else {
              timeAgo = "\(hours) Hour Ago"
          }
      }
      
      if (days > 0) {
          if (days > 1) {
              timeAgo = "\(days) Days Ago"
          } else {
              timeAgo = "\(days) Day Ago"
          }
      }
      
      if(weeks > 0){
          if (weeks > 1) {
              timeAgo = "\(weeks) Weeks Ago"
          } else {
              timeAgo = "\(weeks) Week Ago"
          }
      }
      
      print("timeAgo is===> \(timeAgo)")
      return timeAgo;
  }