I have an NSArray with Store objects. Each Store object has two NSString objects; StoreID and Name. I would like to check quickly if an ID exists in this NSArray with Store objects.

Example:

Store *s1 = [[Store alloc] init];
s1.name = @"Some Name";
s1.id = @"123ABC";

Store *s2 = [[Store alloc] init];
s2.name = @"Some Other Name";
s2.id = @"ABC123";

NSArray *array = [[NSArray alloc] initWithObjects:s1, s2, nil];

NSString *myIdOne = @"ABCDEF";
NSString *myIdTwo = @"123ABC";

BOOL myIdOneExists = ...?
BOOL myIdTwoExists = ...?

Its the ...? I need to figure out. I know I can do this using a for loop and break when found... but this seems to me like an nasty approach since the NSArray could contain thousands of objects,... theoretically.
So I would like to know about a better solution.