银行卡号4位一个空格和显示*号

// 银行卡号转正常号 － 去除4位间的空格
-(NSString *)bankNumToNormalNum:(NSString *)bankCardNumber
{
    return [bankCardNumber stringByReplacingOccurrencesOfString:@" " withString:@""];
}
// 正常号转银行卡号 － 增加4位间的空格
-(NSString *)normalNumToBankNum:(NSString *)bankCardNumber
{
    NSUInteger size = bankCardNumber.length / 4;
    
    /*
    NSUInteger lastLength = bankCardNumber.length % 4;
    NSUInteger surpluLegth = bankCardNumber.length - 4 - lastLength;
    
    NSString *replaceString = @"*";
    for (int i = 1; i < surpluLegth; i ++) {
       replaceString = [NSString stringWithFormat:@"%@*",replaceString];
    }
    
    bankCardNumber = [bankCardNumber stringByReplacingCharactersInRange:NSMakeRange(4, surpluLegth) withString:replaceString];
    */
    
    NSMutableArray *tmpStrArr = [[NSMutableArray alloc] init];
    for (int n = 0;n < size; n++)
    {
        [tmpStrArr addObject:[bankCardNumber substringWithRange:NSMakeRange(n*4, 4)]];
    }
    
    [tmpStrArr addObject:[bankCardNumber substringWithRange:NSMakeRange(size*4, (bankCardNumber.length % 4))]];
    
    bankCardNumber = [tmpStrArr componentsJoinedByString:@" "];
    
    return bankCardNumber;
}