Question

i try to extract only the properties into an array to create a NSPredicate for this.
is there a shorter way for this than creating a mutable array and looping through all objects?

NSMutableArray *extractedIDs = [NSMutableArray array];
for (SomeObject *aObject in self.addedSearchResults) {
    [addedIDs addObject:aObject.someProperty];
}

[NSPredicate predicateWithFormat:@"NOT (someOtherProperty IN %@)", addedIDs]

can’t find something with google (don’t really know how to search this problem)

Answer 1

KVC can help you. Just use:

NSArray* extractedIDs = [self.addedSearchResults valueForKey:@"someProperty"];