How to check if date (from date picker) is between two other dates ? objective-c

问题

i'm trying to get date from UIDatePicker (MM-dd format) and to check if its in the range of two other dates;

i have tried it in so many different ways and i think my mind has gone to far :) can someone help me do it as simple as it should be?

this is my last try code:

NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"MM-dd"];
NSString *theDate = [dateFormat stringFromDate:birthdateSelector.date];
NSDate *birthdate = [dateFormat dateFromString:theDate];

NSString *Capricorn_Start = @"12-22" ;
NSString *Capricorn_End = @"01-19" ;

if ([birthdate laterDate:[dateFormat dateFromString:Capricorn_End]] && [birthdate earlierDate:[dateFormat dateFromString:Capricorn_Start]]){

    NSLog(@"im capricorn");
}

Thanks, Amir.

回答1:

If you have dateA, dateB and dateC, and you want to check if dateA < dateB < dateC, you can get the difference between dateA-dateB and dateB-dateC which will give you diffX and diffY. If diffX sign is equal than diffY sign, it will mean that dateB is between A and C.

Or, in other words, your code would look like this:

NSTimeInterval diffX = [dateB timeIntervalSinceDate:dateA];
NSTimeInterval diffY = [dateC timeIntervalSinceDate:dateB];

if (signbit(diffX) == signbit(diffY))
{
    // dateB is in-between dateA and dateC
}