NSPredicate to filter all items in another set

Question

Is there any way to do this? I have a set of elements that I want to exclude from another set. I know that I could iterate over each element in my set and add it only to my filter if it is not in another set, but it would be nice if I could use the predicate.

A set of elements to exclude is not a set of objects of the same type; This is a set of strings; and I want to exclude anything from my first set if one of the attributes matches this line .... in other words:

NSMutableArray *filteredArray = [NSMutableArray arrayWithCapacity:self.questionChoices.count];

BOOL found;

for (QuestionChoice *questionChoice in self.questionChoices)
{
    found = NO;

    for (Answer *answer in self.answers)
    {
        if ([answer.units isEqualToString:questionChoice.code])
        {
            found = YES;
            break;
        }
    }

    if (!found)
        [filteredArray addObject:questionChoice];
}

Can this be done using a predicate?

Answer 1

:

@"NONE %@.units == code", self.answers

NSArray. self.questions NSArray,

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"NONE %@.units == code", self.answers]

NSArray *results = [self.questions filteredArrayUsingPredicate:predicate];

NSMutableArray,

[self.questions filterUsingPredicate:predicate];

, , . , , .

:
NSArray
NSMutableArray

Answer 2

, Apple . filterArrayUsingPredicate.