Connecting in-cell button direct to view controller

MyTableViewController.m

@implementation MyTableViewController

- (IBAction)checkboxPressed:(UIButton *)button {
    // Figure out which row this checkbox belongs to
    id aView = button.superview;
    while (![aView isKindOfClass:UITableViewCell.class]) {
        aView = [aView superview];
    }
    
    NSIndexPath *row = [self.tableView indexPathForCell:aView];
    // Now can look up the task at that row and work with it
}

@end