Core Data Query Multiple Columns with Single Search String

Question

I have a simple Core Data model with two string attributes (size and category). Given a search string like \'small widget\' is it possible to return records that match all the q

Answer 1

For Swift you can fetch multiple columns by using propertiesToFetch

let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "<YOUR ENTITY NAME>")
let predicate = NSPredicate(format: "<YOUR PREDICATE>")
fetchRequest.predicate = predicate
fetchRequest.resultType = .dictionaryResultType


// Here is where you can query multiple columns, you can add as much columns as you want and fetch them as an array of dictionaries
fetchRequest.propertiesToFetch = ["column1", "column2", "column3, "column4"]


let sort = NSSortDescriptor(key: "column1", ascending: false)
fetchRequest.sortDescriptors = [sort]

Answer 2

I haven't tested it but it looks like your want this:

NSString *search = @"small widget";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%@ contains[cd] size AND %@ contains[cd] category", search, search];

The search string would contain (or not) the size and the category, you should ask if the current size or category is contained on the search string.

You could also split the search string and modify your predicate. You should them to identify the one that performs better

NSString *search = @"small widget";
    NSArray *array = [search componentsSeparatedByString:@" "];
    NSMutableArray *subPredicates = [NSMutableArray array];
    for (NSString *q in array) {
        [subPredicates addObject:
         [NSPredicate predicateWithFormat:@"size contains[cd] %@ OR category contains[cd] %@", q, q]];
    }
    NSCompoundPredicate *predicate = [[[NSCompoundPredicate alloc] initWithType:NSAndPredicateType
                                                                 subpredicates:subPredicates] autorelease];