How can I optimize this search based on Core Data?

Question

How can I optimize this search based on Core Data?

I am trying to search in my application. There are two Core Data objects: "Tag" and "DvarTorah". The tag has only a string. "DvarTorah" has a title, text content and some other properties. I am trying to find the best way to quickly find them. The application has about 1200 DvarTorah objects and even more tags. Right now I am loading NSFetchedResultsController when my view view controller calls viewDidLoad. Then, when the user types in the search field or changes the scope, I call a method that takes both the value of the frame string and the search term and filters my array of objects. Here's what it looks like:

- (void) filterArrayWithSearchTerm:(NSString *)searchString andScopeIndex:(NSInteger)scopeIndex{

    if ([searchString isEqualToString:@""]) {
        return;
    }    

    NSMutableArray *unfilteredResults = [[[[self.fetchedResultsController sections] objectAtIndex:0] objects] mutableCopy];

    if (self.filteredArray == nil){
        self.filteredArray = [[[NSMutableArray alloc ] init] autorelease];
    }

    [filteredArray removeAllObjects];

    NSPredicate *predicate = [[[NSPredicate alloc] init] autorelease];

    if (scopeIndex == 0) {
        predicate = [NSPredicate predicateWithFormat:@"dvarTorahTitle CONTAINS[cd] %@", searchString];
    }else if (scopeIndex == 1) {
        predicate = [NSPredicate predicateWithFormat:@"searchableContent CONTAINS[cd] %@", [searchString canonicalString]];            
    }else if (scopeIndex == 2){
        predicate = [NSPredicate predicateWithFormat:@"ANY tags.tagText CONTAINS[cd] %@", searchString];
    }else{
        predicate = [NSPredicate predicateWithFormat:@"(ANY tags.tagText CONTAINS[cd] %@) OR (dvarTorahTitle CONTAINS[cd] %@) OR (searchableContent CONTAINS[cd] %@)", searchString,searchString,searchString];
    }

    for (DvarTorah *dvarTorah in unfilteredResults) {
        if ([predicate evaluateWithObject:dvarTorah]) {
            [self.filteredArray addObject:dvarTorah];
        }
    }

    [unfilteredResults release];
}

, . , CONTAINS , ( searchableContent) . ?

Edit:

, :

    if ([searchString isEqualToString:@""]) {
    return;
}

if (self.filteredArray == nil) {
    self.filteredArray = [[[NSMutableArray alloc ] init] autorelease];
}

[filteredArray removeAllObjects];

NSPredicate *predicate = nil;

if (scopeIndex == 0) {
    predicate = [NSPredicate predicateWithFormat:@"dvarTorahTitle CONTAINS[cd] %@", searchString];
}else if (scopeIndex == 1) {
    predicate = [NSPredicate predicateWithFormat:@"searchableContent CONTAINS[cd] %@", [searchString canonicalString]];            
}else if (scopeIndex == 2){
    predicate = [NSPredicate predicateWithFormat:@"ANY tags.tagText CONTAINS[cd] %@", searchString];
}else{
    predicate = [NSPredicate predicateWithFormat:@"(ANY tags.tagText CONTAINS[cd] %@) OR (dvarTorahTitle CONTAINS[cd] %@) OR (searchableContent CONTAINS[cd] %@)", searchString,searchString,searchString];
}

[self.filteredArray addObjectsFromArray:[[[[[self.fetchedResultsController sections] objectAtIndex:0] objects] mutableCopy] filteredArrayUsingPredicate:predicate]];

}

Edit2:

, :

- (void) filterArrayWithSearchTerm:(NSString *)searchString andScopeIndex:(NSInteger)scopeIndex{

    if ([searchString isEqualToString:@""]) {
        return;
    }

    if (self.filteredArray == nil) {
        self.filteredArray = [[[NSMutableArray alloc ] init] autorelease];
    }

    [filteredArray removeAllObjects];

    NSPredicate *predicate = nil;

    if (scopeIndex == 0) {
        predicate = [NSPredicate predicateWithFormat:@"dvarTorahTitle CONTAINS[cd] %@", searchString];
    }else if (scopeIndex == 1) {
        predicate = [NSPredicate predicateWithFormat:@"searchableContent CONTAINS[cd] %@", [searchString canonicalString]];            
    }else if (scopeIndex == 2){
        predicate = [NSPredicate predicateWithFormat:@"ANY tags.tagText CONTAINS[cd] %@", searchString];
    }else{
        predicate = [NSPredicate predicateWithFormat:@"(ANY tags.tagText CONTAINS[cd] %@) OR (dvarTorahTitle CONTAINS[cd] %@) OR (searchableContent CONTAINS[cd] %@)", searchString,searchString,searchString];
    }

    [self.filteredArray addObjectsFromArray:[[[[self.fetchedResultsController sections] objectAtIndex:0] objects] filteredArrayUsingPredicate:predicate]];
}