Using NSPredicate to determine if a string equals another string

Question

I have an NSArray of CalEvents returned with the [CalCalendarStore eventPredicateWithStartDate] method. From the events returned, I am trying to keep only those in which the title of the event == @"on call" (case-insensitive).

I am able to keep in the array those events whose title includes @"on call" with the following code (where 'events' is a 'NSArray' populated with CalEvents):

NSPredicate *onCallPredicate = [NSPredicate predicateWithFormat:@"(SELF.title CONTAINS[c] 'on call')"];
[events filteredArrayUsingPredicate:onCallPredicate];

I've tried using a predicate format string like:

@"SELF.title == 'on call'" but this doesn't seem to work.

Is there an easier way to do this?

Solution 1

Try [NSPredicate predicateWithFormat:@"title ==[c] 'on call'"];

(The [c] makes the equality comparison case-insensitive.)

Solution 2

Try predicate with format @"self.title like[c] 'on call'". The following sample code outputs 2 strings:

NSArray* ar = [NSArray arrayWithObjects:@"on call", @"I'm on call", @"lala", @"On call", nil];
NSArray* filt = [ar filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self like[c] 'on call'"]];
NSLog([filt description]);

//Output
"on call",
"On call"

Comments

[Dave DeLong]

+1, although you could throw the [c] modifier after the == to make it case-insensitive.

[Cory Kilger]

Edited it to be case-insensitive.

[Garry Pettet]

Is there a difference between using == and like for string comparisons?

[Vladimir]

Looks like in your case the work they same. But if you want to use wildcards in string comparison then '==' won't work and you'll need to use LIKE instead.

[Samuel]

Just curious, will MATCH[n] work for == when used without any (*?.) wildcards?