Question

How do you make an NSPredicate that finds all objects in an array that contain a certain letters?

NSMutableArray *testArray = [[NSMutableArray alloc] initWithObjects:@"abc",@"cba", @"bca", nil];

NSPredicate *p = [NSPredicate predicateWithFormat:@"SELF contains[cd] %@",@"abc"];

NSMutableArray *result = (NSMutableArray *)[testArray filteredArrayUsingPredicate: p];

Result only contains one object, @”abc”… I want it to catch all words that have “abc” in them. (e.g “cba”, “cba”, “lllllllllbbacllllll” etc)..

Answer 1

There’s nothing wrong with the other answers. However, I wanted to suggest a different way to create the predicate: using a block.

NSArray *testArray = @[@"abc", @"cba", @"cda"];
NSArray *letters = @[@"a", @"b", @"c"];

NSPredicate *p = [NSPredicate predicateWithBlock:^BOOL(id string, NSDictionary *bindings) {
    for ( NSString *letter in letters ) {
        NSStringCompareOptions options = NSCaseInsensitiveSearch | NSDiacriticInsensitiveSearch;
        if ( ! [string rangeOfString:letter options:options].length ) {
            return NO;
        }
    }
    return YES;
}];
NSArray *result = [testArray filteredArrayUsingPredicate:p];

And just for the fun, you can also write the predicate with a subquery. This is less efficient but it’s the shorter solution.

NSArray *testArray = @[@"abc", @"cba", @"bcda"];
NSArray *letters = @[@"a", @"b", @"c"];

NSPredicate *p = [NSPredicate predicateWithFormat:@"SUBQUERY(%@, $a, self CONTAINS[cd] $a)[SIZE] == %d", letters, letters.count];
NSArray *result = [testArray filteredArrayUsingPredicate:p];