/**
   *  正则表达式 判断字符串内容是否是有效数字
   *
   *  @param string 需要验证的字符串
   *
   *  @return 字符串内容是否是有效数字
   */
  - (BOOL)validateNumberByRegExp:(NSString *)string {
      BOOL isValid = YES;
      NSUInteger len = string.length;
      if (len > 0) {
          NSString *numberRegex = @"^[0-9]*$";
          NSPredicate *numberPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",numberRegex];
          isValid = [numberPredicate evaluateWithObject:string];
      }
      return isValid;
 }