iphone - 如何获取从 NSDate 到现在的天数？

Question

我对已创建的日期进行了一些评论，因此我希望该日期为天数，之后为月数。这是我得到日期的代码：

NSDateFormatter * inputFormatter = [[NSDateFormatter alloc] init];
[inputFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss" ];

NSString * inputString = entry.createdAt;
NSDate * inputDate = [inputFormatter dateFromString:inputString];
double  timeInterval = [inputDate timeIntervalSinceNow];
dateLabel.text = [NSString stringWithFormat:@"%d",timeInterval];

Answer 1

日子很简单：

int days = timeInterval / (60.0 * 60.0 * 24.0); //< i.e. divide by seconds in a day

几个月更难。你希望它真的很准确吗？还是假设一个月有 30 天呢？如果是这样，那么它只是：

int months = timeInterval / (60.0 * 60.0 * 24.0 * 30.0); //< i.e. divide by seconds in a month

要将所有内容包装在一起，您可以执行以下操作：

if (timeInterval < (60.0 * 60.0 * 24.0 * 30.0)) {
    dateLabel.text = [NSString stringWithFormat:@"%i days", (int)(timeInterval / (60.0 * 60.0 * 24.0))];
} else {
    dateLabel.text = [NSString stringWithFormat:@"%i months", (int)(timeInterval / (60.0 * 60.0 * 24.0 * 30.0))];
}

那是你要的吗？

Answer 2

您应该查看 NSCalendar components:fromDate:toDate:options方法。

    NSDate *date = [[[NSDate alloc] init] autorelease];
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDateComponents *components = [calendar components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:date toDate:inputDate options:0];
    int years = [components year];
    int months = [components month];
    int days = [components day];
    NSLog(@"Start date: %@ End Date: %@", date, inputDate);
    NSLog(@"year: %i months: %i days: %i", years, months, days);
    [date release];
    [calendar release];