NSPredicate to Search Collection - ios

Question

I have a tableview with a search bar. I was able to use NSPredicate to search the tableview when I add the items to another array:
for(head in items){
[desc addObject:head.DESC];
[category addObject:head.CATEGORY];
}
- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:#"self CONTAINS[cd] %#", searchText];
searchResults = [desc filteredArrayUsingPredicate:resultPredicate];
}
Now I want to keep the collection together so that a tableView didSelectRowAtIndexPath will be able to use the category object.
I load my table view like this:
for (int i = 0; i < [items count]; i++){
head = [items objectAtIndex:indexPath.row];
labelName.text = head.DESC;
How can I get my NSPredicate to search the collection for head.DESC?
#pragma mark Search Results
- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:#"self CONTAINS[cd] %#", searchText];
searchResults = [items filteredArrayUsingPredicate:resultPredicate];
}
Currently, I am getting this exception when running the above code.
reason: 'Can't use in/contains operator with collection <Order: 0x7b22e900> (not a collection)'

Answer 1

I think I understand your question. You want to be able to filter your items array (which is a bunch of heads) by the DESC property. How about using blocks?
- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
NSPredicate *resultPredicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
return [[evaluatedObject DESC] containsString:searchText];
}];
searchResults = [items filteredArrayUsingPredicate:resultPredicate];
}
If your Order object defines DESC as a #property (or is otherwise KVC Compliant), you'll be able to just access it directly. This should work:
- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:#"self.DESC CONTAINS[cd] %#", searchText];
searchResults = [items filteredArrayUsingPredicate:resultPredicate];
}

Answer 2

I think it helps you:
- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:#"ANY self.DESC CONTAINS[cd] %#", searchText];
searchResults = [items filteredArrayUsingPredicate:resultPredicate];
}