[objective-C] get time between two times of the day

Question

Hey,

I've already tried with NSDate but with no luck. I want the difference between for example 14:10 and 18:30.

Hours and minutes.

I Hope you can help me shouldn't be that complicated :)

Answer 1

The NSDate class has a method timeIntervalSinceDate that does the trick.

NSTimeInterval secondsBetween = [firstDate timeIntervalSinceDate:secondDate];

NSTimeInterval is a double that represents the seconds between the two times.

Answer 2

Here's my quick solution:

NSDateFormatter *df = [[[NSDateFormatter alloc] init] autorelease];
[df setDateFormat:@"HH:mm"];
NSDate *date1 = [df dateFromString:@"14:10"];
NSDate *date2 = [df dateFromString:@"18:09"];
NSTimeInterval interval = [date2 timeIntervalSinceDate:date1];
int hours = (int)interval / 3600;             // integer division to get the hours part
int minutes = (interval - (hours*3600)) / 60; // interval minus hours part (in seconds) divided by 60 yields minutes
NSString *timeDiff = [NSString stringWithFormat:@"%d:%02d", hours, minutes];

Answer 3

This code works great. Only one exception. What if you want to find the difference between 23:30 and 02:30? The current code returns a -21:00. Is there a way to maybe add 24 hours (86400) to the result? I've been trying but I can't find the solution.

Answer 4

There's no need to calculate this by hand, take a look at NSCalendar. If you want to get the hours and minutes between two dates, use something like this:

NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSUInteger unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit;
NSDateComponents *components = [gregorianCalendar components:unitFlags
                                                    fromDate:firstDate
                                                      toDate:otherDate
                                                     options:0];
[gregorianCalendar release];

You now have the hours and minutes as NSDateComponents and can access them as NSIntegers like [components hour] and [components minute]. This will also work for hours between days, leap years and other fun stuff.

Answer 5

The Gregorian solution is very nice, clean and elegant. Thank YOu