retain return value from invocation

gistfile1.m

    NSString *selectorString = [NSString stringWithFormat:@"cellForSection%dRow%d:",indexPath.section,indexPath.row];
    SEL cellSelector = NSSelectorFromString(selectorString);
    if ([self respondsToSelector:cellSelector]) {
        
        NSInvocation * invocation = [ NSInvocation new ];
        NSMethodSignature *signature;

        CFTypeRef result = NULL;
        signature = [self.class instanceMethodSignatureForSelector:cellSelector];
        invocation = [NSInvocation invocationWithMethodSignature:signature];
        [invocation setSelector:cellSelector];
        [invocation setArgument:&indexPath atIndex:2];
        [invocation invokeWithTarget:self];
        [invocation getReturnValue:&result];

        UITableViewCell *returnedCell = (__bridge UITableViewCell *)result;
        return returnedCell;
    }