I have two NSDate objects and I want the difference between the two and the result should again be a NSDate object. Any idea how to achieve this?
Here, I am trying to address a unique problem where I have to find out the elapsed time and then localize the elapsed time. I can localize it if I have the elapsed time in NSDate object. So thought of creating a NSDate object which has its time component same as time interval between the two dates so that I could use NSDateFormatter to localize it.
NSDate
represents an instance in time, so it doesn't make sense to represent an interval of time as an NSDate
. What you want is NSDateComponents
:
NSDate *dateA;
NSDate *dateB;
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *components = [calendar components:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay
fromDate:dateA
toDate:dateB
options:0];
NSLog(@"Difference in date components: %i/%i/%i", components.day, components.month, components.year);
If you subtract 12/12/2001 from 05/05/2002 what will be the date? The chronological distance between two dates can't be a date, it's alway some kind of interval. You can use timeIntervalSinceDate: to calculate the interval.
To localize you can try the following steps:
You can use the NSCalendar with dateFromComponents: passing in a NSDateComponents .
To break down a timeInterval into NSDateComponents look at How do I break down an NSTimeInterval into year, months, days, hours, minutes and seconds on iPhone? .
Finally use the NSDateFormatter and initWithDateFormat:allowNaturalLanguage: to get your localized string. The Date Format String Syntax shows the different placeholders.
From NSDate
class reference, you have instance methods to do these -
isEqualToDate:
timeIntervalSinceDate:
您可以使用NSDate
的timeIntervalSinceDate:
计算两个日期之间的时间间隔,但是将时间间隔表示为日期没有任何意义。
There is a easy way by using -compare: in NSDate:
NSDate *dateA = [NSDate dateWithTimeIntervalSinceNow:100];
NSDate *dateB = [NSDate dateWithTimeIntervalSinceNow:200];
NSDate *myDate = [NSDate dateWithTimeIntervalSinceNow:150];
NSArray *dateArray = [NSArray arrayWithObjects:dateA, dateB, myDate, nil];
NSArray *sortedArray = [dateArray sortedArrayUsingSelector:@selector(compare:)];
if ([myDate isEqualToDate:[sortedArray objectAtIndex:1]])
NSLog(@"myDatea between dateA and dateB");
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.