Comparing two dates in Objective-C [duplicate] - objective-c

Question

This question already has answers here:
How to compare two NSDates: Which is more recent?
(13 answers)
Closed 9 years ago.
I need to compare the current date/time against user selected date/time.
Below is my code snippet
-(IBAction)btnSaveTouched:(id)sender {
NSDate *today = [NSDate date];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd H:mm"];
NSString *formatterDate = [formatter stringFromDate: today];
NSComparisonResult comparisionResult1 = [self.paramSchedule1StartSQLDateString compare:formatterDate];
if (comparisionResult1 == NSOrderedAscending) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error" message:#"Viewing schedule must be after current time." delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
return;
}
NSLog(#"comparisionResult1 %d", comparisionResult1);
}
After btnSaveTouched(UIButton) is tap, the date/time will be store into the database and return back to the screen. (view controller where user select the date/time)
However, when I tried to compare another date/time, the alert will be show even though I selected date/time later then the current date/time.
After NSLog the comparsionResult1, the value is 1 for the second time checking always.
I tried to do this NSComparsionResult comparisionResult1 = 0; but it's not working properly. Is there any ways to go about doing this?
Please advise.
Thanks

Answer 1

Comparison between dates you need to be careful, expecially If you compare with NSString, you must make sure both dates are arranged, and you need to be careful with both formats..So i recomend you compare two NSDate.
Sample:
NSDate *date1 = //…
NSDate *date2 = //…
switch ([date1 compare:date2]) {
case NSOrderedAscending:
//Do your logic when date1 > date2
break;
case NSOrderedDescending:
//Do your logic when date1 < date2
break;
case NSOrderedSame:
//Do your logic when date1 = date2
break;
}
Of course, you can implement a category for NSDate. But already exists, and i like to use this one: NSDate Category, witch you can edit and customize as you wish.

Answer 2

Try this code for any comparison between dates... You should not compare date in the form of string. Compare the dates before conversion to string. Convert the self.paramSchedule1StartSQLDateString into date format using dateFromString function of the formatter by specifying the exact date format as that of the dateString. Then compare the dates using following function.
NSDate *today = [NSDate date]; // current date
NSDate *newDate = self.paramSchedule1StartSQLDateString; // other date
NSComparisonResult result;
result = [today compare:newDate]; // comparing two dates
if(result == NSOrderedAscending)
NSLog(#"today is less");
else if(result == NSOrderedDescending)
NSLog(#"newDate is less");
else if(result == NSOrderedSame)
NSLog(#"Both dates are same");
else
NSLog(#"Date cannot be compared");

Answer 3

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:#"yyyy-MM-dd"];
NSDate *date1 = [dateFormatter dateFromString:TodayDate];
NSDateFormatter *dateFormatte = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatte setDateFormat:#"yyyy-MM-dd"];
NSDate *date2 = [dateFormatte dateFromString:CompareDate];
unsigned int unitFlags = NSDayCalendarUnit;
NSCalendar *gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [gregorian components:unitFlags fromDate:date1 toDate:date2 options:0];
int days = [comps day];
NSLog(#"%d",days);