银行卡只显示后4位明文处理方法

-(NSString *)returnBankCard:(NSString *)BankCardStr{

self.originString = BankCardStr;
   BankCardStr = [self getValidStringWithString:BankCardStr];
if (BankCardStr.length > 5) {
    NSString *formerStr = [BankCardStr substringToIndex:0];
                    NSString *str1 = [BankCardStr stringByReplacingOccurrencesOfString:formerStr withString:@""];
                    NSString *endStr = [BankCardStr substringFromIndex:BankCardStr.length-4];
                    endStr = [self  getValidStringWithString:endStr];
                    NSString *str2 = [str1 stringByReplacingOccurrencesOfString:endStr withString:@""];
                    NSString *middleStr = [str2 stringByReplacingOccurrencesOfString:str2 withString:@"**** **** **** "];
                    NSString *CardNumberStr = [formerStr stringByAppendingFormat:@"%@%@",middleStr,endStr];
                    return CardNumberStr;
}else {
    return BankCardStr;
}

}

• (NSString *)getValidStringWithString:(NSString *)string {
  NSString *returnString = string;

  if (![returnString isKindOfClass:[NSString class]]) {
  returnString = @"";
  }

  if (returnString.length <= 0) {
  returnString = @"";
  }

  NSString *noSpaceString = [returnString copy];
  returnString = [noSpaceString stringByReplacingOccurrencesOfString:@" " withString:@""];
  if (noSpaceString.length <= 0) {
  returnString = @"";
  }

  return returnString;
  }