Writing a simple NSpredicate - Logic Issue

问题

I have a Person object. and this person object has the following attributes;

Name
StartDate
EndDate

I am saving this Person objects to an array. This array might contain more than 100 person objects.

The following is an example of person objects in that array;

John, Tue Feb 22, Thr Mar 30
Jack, Wed Mar 09, Fri Apr 21
Jack, Thu Mar 19, Fri Dec 20
Jack, Tue Jan 08, Fri Apr 26 etc..

Now i need to will supply a date, say for example Wed 29 Mar, and i need to check if it's in the range of StartDate and EndDate in the array of persons object. How can i do this ? My working are as follows, but it doesn't work (It gives incorrect results)

NSPredicate *datePred = [NSPredicate predicateWithFormat:@"StartDate>= %@ && EndDate<= %@",givenDate,givenDate];
            resultArray = [arrayContainingAllPersonObjects filteredArrayUsingPredicate:datePred ];

I also tried the following method, but it too gives incorrect results (which was taken off a SO post);

NSPredicate *greaterThanPredicate = [NSPredicate predicateWithFormat:@"StartDate<= %@", providedDate"];
NSPredicate *lessThanPredicate = [NSPredicate predicateWithFormat:@"EndDate>= %@", ProvidedDate"];
NSPredicate *betweenPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:greaterThanPredicate, lessThanPredicate, nil]];

I have no clue as in what is causing this, Help

回答1:

Are the StartDate and EndDate NSDate objects?

I'd suggest giving this writeup about predicates a look. It has helped me reduce my filtering and searching code to a few lines: http://www.cocoanetics.com/2010/03/filtering-fun-with-predicates/

回答2:

Try using '%@' like StartDate = '%@' && EndDate ='%@'

UPD:

Try

NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"StartDate = '%@', startDateHere]];

来源：https://stackoverflow.com/questions/10307902/writing-a-simple-nspredicate-logic-issue

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iphone

objective-c

nspredicate