Ios NSComponents组件：fromDate:toDate:选项：度量小时还是天？

编辑：请标记为重复，找到答案

所以我想看看自从用户上次发布一个对象以来，这一天是否已经过去了。如果我使用

NSCalendarUnit units = NSDayCalendarUnit;
NSDateComponents *components = [calendar components:units fromDate:lastPostDate toDate:now options:0];

示例：

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用户在晚上9点发布对象。然后我在第二天早上8点（11小时后）运行上述方法。它会告诉我0天已经过去了，对吗？如果是这样的话，有没有一种方法可以告诉我我想找出什么，或者我应该手动去做呢？

试试这个方法，我希望它能帮上忙

- (NSString*)getTimeDifferenceFromCurrentDate:(NSDate *) lastPostDate {
    NSDate *currentDate = [NSDate date];

    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit|NSWeekCalendarUnit fromDate:messageDate toDate:currentDate options:0];


    NSString *strTime = @"";

    /*if (components.day > 0 || components.week >= 1) {
     if (components.day >= 1||components.week >= 1||components.month >= 1){
     NSDateFormatter *dfForCell = [[NSDateFormatter alloc] init];

     [dfForCell setDateFormat:@"MMM dd, yyyy"];
     NSLocale*  my24HourLocale = [[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"] autorelease];
     [dfForCell setLocale:my24HourLocale];
     NSString *aStrFinalDate  = [dfForCell stringFromDate:messageDate];
     strTime = [NSString stringWithFormat:@"%@", aStrFinalDate];
     };
     }*/
    if (components.year > 0) {
        if (components.year > 1)
            strTime = [NSString stringWithFormat:@"%d years ago", components.year];
        else
            strTime = [NSString stringWithFormat:@"%d year ago", components.year];
    }
    else if (components.month > 0) {
        if (components.month > 1)
            strTime = [NSString stringWithFormat:@"%d months ago", components.month];
        else
            strTime = [NSString stringWithFormat:@"%d month ago", components.month];
    }
    else if (components.week > 0) {
        if (components.week > 1)
            strTime = [NSString stringWithFormat:@"%d weeks ago", components.day];
        else
            strTime = [NSString stringWithFormat:@"%d day ago", components.day];
    }
    else if (components.day > 0) {
        if (components.day > 1)
            strTime = [NSString stringWithFormat:@"%d days ago", components.day];
        else
            strTime = [NSString stringWithFormat:@"%d day ago", components.day];
    }
    else if (components.hour > 0) {
        if (components.hour > 1)
            strTime = [NSString stringWithFormat:@"%dhours ago", components.hour];
        else
            strTime = [NSString stringWithFormat:@"%dhour ago", components.hour];
    }
    else if (components.minute > 0) {
        if (components.minute > 1)
            strTime = [NSString stringWithFormat:@"%dmin ago", components.minute];
        else
            strTime = [NSString stringWithFormat:@"%dmin ago", components.minute];
    }
    else if (components.second > 0) {
        if (components.second > 1)
            strTime = [NSString stringWithFormat:@"%dsec ago", components.second];
        else
            strTime = [NSString stringWithFormat:@"%dsec ago", components.second];
    }
    else {
        strTime = @"1 sec ago";
    }
    return strTime;
}

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我做到了，得到了我认为会得到的。我原封不动地发布了这个问题，因为我想让它保持开放状态，以防有一个选项/方法来做我想做的事情。另外，我的新手对这一点的信心让我怀疑自己。与其只是展示一堆代码，不如解释一下这是如何回答张贴的问题的。