在iOS上使用NSDate的人类友好的日期描述

func formattedHumanReadable(date: NSDate) -> String {
    let formatter = NSDateFormatter()
    formatter.timeStyle = .NoStyle
    formatter.dateStyle = .ShortStyle
    formatter.doesRelativeDateFormatting = true

    let locale = NSLocale.currentLocale()
    formatter.locale = locale

    return formatter.stringFromDate(date)
  }

NSDateFormatter *dateFormatter = ...;
dateFormatter.doesRelativeDateFormatting = YES;

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setTimeStyle:NSDateFormatterNoStyle];
    [dateFormatter setDateStyle:NSDateFormatterMediumStyle];

    NSLocale *locale = [NSLocale currentLocale];
    [dateFormatter setLocale:locale];

    [dateFormatter setDoesRelativeDateFormatting:YES];

timeAgoSinceNow

NSDate.init(timeIntervalSinceNow:-3600).timeAgoSinceNow()         \"An hour ago\"
 NSDate.init(timeIntervalSinceNow:-3600*24).timeAgoSinceNow()      \"Yesterday\"
 NSDate.init(timeIntervalSinceNow:-3600*24*6).timeAgoSinceNow()    \"6 days ago\"
 NSDate.init(timeIntervalSinceNow:-3600*24*7*3).timeAgoSinceNow()  \"3 weeks ago\"
 NSDate.init(timeIntervalSinceNow:-3600*24*31*3).timeAgoSinceNow() \"3 months ago\"

timeAgoSinceDate

NSDateFormatter

doesRelativeDateFormatting