为什么我不能使用prepareForSegue传递值？

我有两个UIViewControllers.在A ViewController我有代码:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:@"ToResetPwd_NumberSegue"])
{
    ResetPwdBySmsCodeViewController* vc = (ResetPwdBySmsCodeViewController*)[segue destinationViewController];
    vc.phone_no = _TF_phoneOrEmail.text;//TF_phoneOrEmail is a UITextField
    vc.test = @"dagaga";
}

}

在B .h我有代码

@interface ResetPwdBySmsCodeViewController : UIViewController
@property (weak, nonatomic) NSString *phone_no;
@property (weak, nonatomic) NSString *test;
@end

在B .m

我可以得到_test,但不是_phone_no

我相信这vc.phone很好prepareForSegue