来自NSDate的相对字符串

Question

有没有人知道一个库或什么会将NSDate转换成字符串,如下面的例子？

1 hour ago
yesterday
last Thursday
2 days ago
last month
6 months ago
last year

Answer 1

NSDateFormatter将在一个实例上使用setDoesRelativeDateFormatting:执行上面提到的大量操作.从那里,您可以使用日期样式和时间样式控制格式,以根据您的需要进行微调.

如果这不能满足您的需求,那么请查看SORelativeDateTransformer,它是一个NSValueTransformer子类,它试图提供与SO相关日期相同的行为.

最后,如果你想自己动手或在这里做更多的研究是关于这个话题的(可能的)原始问题...... 是的,它是问题11.

Answer 2

对于后代,这里是一个NSDate类别方法,我使用由David链接的Stack Overflow相关性计算以及其他类似SO问题拼凑的其他提示:

- (NSString *)relativeDateString
{
    const int SECOND = 1;
    const int MINUTE = 60 * SECOND;
    const int HOUR = 60 * MINUTE;
    const int DAY = 24 * HOUR;
    const int MONTH = 30 * DAY;

    NSDate *now = [NSDate date];
    NSTimeInterval delta = [self timeIntervalSinceDate:now] * -1.0;

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger units = (NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit);
    NSDateComponents *components = [calendar components:units fromDate:self toDate:now options:0];

    NSString *relativeString;

    if (delta < 0) {
        relativeString = @"!n the future!";

    } else if (delta < 1 * MINUTE) {
        relativeString = (components.second == 1) ? @"One second ago" : [NSString stringWithFormat:@"%d seconds ago",components.second];

    } else if (delta < 2 * MINUTE) {
        relativeString =  @"a minute ago";

    } else if (delta < 45 * MINUTE) {
        relativeString = [NSString stringWithFormat:@"%d minutes ago",components.minute];

    } else if (delta < 90 * MINUTE) {
        relativeString = @"an hour ago";

    } else if (delta < 24 * HOUR) {
        relativeString = [NSString stringWithFormat:@"%d hours ago",components.hour];

    } else if (delta < 48 * HOUR) {
        relativeString = @"yesterday";

    } else if (delta < 30 * DAY) {
        relativeString = [NSString stringWithFormat:@"%d days ago",components.day];

    } else if (delta < 12 * MONTH) {
        relativeString = (components.month <= 1) ? @"one month ago" : [NSString stringWithFormat:@"%d months ago",components.month];

    } else {
        relativeString = (components.year <= 1) ? @"one year ago" : [NSString stringWithFormat:@"%d years ago",components.year];

    }

    return relativeString;
}

Answer 3

请勿使用您自己的自定义字符串翻译.编写自己的翻译就像"3秒前"一样,不仅存在需要不断更新的问题,而且还没有本地化为其他语言.

相反,使用Apple内置的NSDateFormatter:

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.doesRelativeDateFormatting = YES;
formatter.locale = [NSLocale currentLocale];
formatter.dateStyle = NSDateFormatterShortStyle;
formatter.timeStyle = NSDateFormatterShortStyle;
NSString *timeString = [formatter stringFromDate:self.date];

这将输出类似"今天,晚上11点10分"或"7/17/14,5:44 AM"的内容.