- (IBAction)saveEmailAction:(id)sender {
     if ([self  isValidateEmail:_mailField.text])
     {
         [self.delegate saveEmail:_mailField.text];
         [self.navigationController popViewControllerAnimated:YES];
     }
    else
    {
        UIAlertView *error=[[UIAlertView alloc]initWithTitle:@"提示" message:@"請輸入正確郵箱" delegate:self cancelButtonTitle:@"確定" otherButtonTitles:nil];
        [error show];
    }
}


-(BOOL)isValidateEmail:(NSString *)email {
    NSString *emailRegex = @"[A-Z0-9a-z._%+-]
 
[email protected][A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
    return [emailTest evaluateWithObject:email];
}