NSPredicate format specifiers issue

Question

I use this predicate:

NSPredicate *offencePredicate =
    [NSPredicate predicateWithFormat:@"(%@ == %@) AND (%@ == %d)", kTeamID, self.selectedTeam.teamID, kPlayerZoneID, ZoneIdTypeOffence];

but the predicate is:

"teamID" == 10 AND "playerZoneID" == 3

instead of:

teamID == 10 AND playerZoneID == 3

How can I trim this "" when I use format specifiers for predicating. And the next question is: is this the right solution using form specifiers in predicate. Because I have some API keys that are correspond to my core data entries attributes. So it is ok to use constant string that will allow quite faster changes if I need to change some of these keys, but is it ok to use this constant for predication?

Answer 1

You need to use %K for the keys.

It would look like this:

[NSPredicate predicateWithFormat:@"(%K == %@) AND (%K == %d)", kTeamID, self.selectedTeam.teamID, kPlayerZoneID, ZoneIdTypeOffence];

Answer 2

Use %K.

See this example from the documentation:

NSString *attributeName = @"firstName";
NSString *attributeValue = @"Adam";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%K like %@",
    attributeName, attributeValue];

Result:

firstName like "Adam"