iphone - 比较 NSDate 的某些组件？

Question

如何仅比较 2 个 NSDate 的年月日组件？

Answer 1

因此，您可以这样做:

NSCalendar *calendar = [NSCalendar currentCalendar];
NSInteger desiredComponents = (NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit);

NSDate *firstDate = ...; // one date
NSDate *secondDate = ...; // the other date

NSDateComponents *firstComponents = [calendar components:desiredComponents fromDate:firstDate];
NSDateComponents *secondComponents = [calendar components:desiredComponents fromDate:secondDate];

NSDate *truncatedFirst = [calendar dateFromComponents:firstComponents];
NSDate *truncatedSecond = [calendar dateFromComponents:secondComponents];

NSComparisonResult result = [truncatedFirst compare:truncatedSecond];
if (result == NSOrderedAscending) {
  //firstDate is before secondDate
} else if (result == NSOrderedDescending) {
  //firstDate is after secondDate
}  else {
  //firstDate is the same day/month/year as secondDate
}

基本上，我们获取两个日期，去掉它们的小时-分钟-秒位，然后将它们转回日期。然后我们比较这些日期(不再有时间部分；只有日期部分)并查看它们之间的比较情况。

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