Objective-C

NSPredicate *predicate = [NSPredicate predicateWithBlock:^BOOL(id item,

NSDictionary *bindings) { return [item isKindOfClass:[UILabel class]];

}];

Swift

let predicate = NSPredicate { (item, bindings) -> Bool in
    return item.isKindOfClass(UILabel.self)
}

In this example, the predicate will match items that are of the class UILabel.