Question

I am filtering an array that can have many objects with a predicate. I would like to limit the results returned for performance reasons. The array is not sorted, so once the limit is hit, I would like the search to stop.

Is this possible? I am not sure if by means of predicate directive or otherwise.

Answer 1

I think you can use this combination of indexesOfObjectsPassingTest and objectsAtIndexes:

NSUInteger count = 0;
NSUInteger limit = ...;
NSIndexSet *set = [myArray indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
    BOOL pass = ... // check if object passes test;
    if (pass) {
        count++;
        if (count >= limit)
            *stop = YES;  // stops further processing of the array
    }
    return pass;
}];

NSArray *filteredArray = [myArray objectsAtIndexes:set];