iOS -- 十进制、十六进制字符串，byte，data等之间的转换

十进制->十六进制
Byte bytes[]={0xA6,0x27,0x0A};
NSString *strIdL  = [NSStringstringWithFormat:@"%@",[[NSStringalloc]initWithFormat:@"%02lx",(long)bytes[]]];
十六进制->十进制
NSString *rechargeInfo =  @"0xff055008";
NSString *cardId2 = [rechargeInfosubstringWithRange:NSMakeRange(,)];
cardId2 = [NSStringstringWithFormat:@"%ld",strtoul([cardId2UTF8String],,)];

NSString
 *str = @"0xff055008";

//先以16为参数告诉strtoul字符串参数表示16进制数字，然后使用0x%X转为数字类型

unsignedlongred
 = strtoul([str UTF8String],,);

//strtoul如果传入的字符开头是“0x”,那么第三个参数是0，也是会转为十六进制的,这样写也可以：

unsignedlongred
 = strtoul([@"0x6587"UTF8String],,);

NSLog(@"转换完的数字为：%lx",red);
#pragma mark --字符串处理方法
//字符串处理方法
+(NSString *)cutString:(NSString *)str{
    NSString *targetStr=nil;
    if (str.length>) {
        targetStr=[str substringFromIndex:];

    }
    return targetStr;
}
+(NSString *)transToStr:(NSData *)data{

    NSString *str=[NSStringstringWithFormat:@"%@",data];
    return str;
}

//字符串补零操作
+(NSString *)addZero:(NSString *)str withLength:(int)length{
    NSString *string = nil;
    if (str.length==length) {
        return str;
    }
    if (str.length<length) {
        NSUInteger inter = length-str.length;
        for (int i=;i< inter; i++) {
            string = [NSString stringWithFormat:@"0%@",str];
            str = string;
        }
    }
    return string;
}

+(NSString *)stringFromHexString:(NSString *)hexString {//

    char *myBuffer = (char *)malloc((int)[hexStringlength] /  +);
    bzero(myBuffer, [hexString length] /  + );
    for (int i =; i < [hexString length] - ; i += ) {
        unsigned int anInt;
        NSString * hexCharStr = [hexString substringWithRange:NSMakeRange(i, )];
        NSScanner * scanner = [[NSScanneralloc] initWithString:hexCharStr] ;
        [scanner scanHexInt:&anInt];
        myBuffer[i / ] = (char)anInt;
        NSLog(@"myBuffer is %c",myBuffer[i /] );
    }
    NSString *unicodeString = [NSStringstringWithCString:myBuffer encoding:];
    NSLog(@"———字符串=======%@",unicodeString);
    return unicodeString;
}

//10进制转16进制
+(NSString *)ToHex:(longlong int)tmpid
{
    NSString *nLetterValue;
    NSString *str =@"";
    long longint ttmpig;
    for (int i =; i<; i++) {
        ttmpig=tmpid%;
        tmpid=tmpid/;
        switch (ttmpig)
        {
            case :
                nLetterValue =@"A";break;
            case :
                nLetterValue =@"B";break;
            case :
                nLetterValue =@"C";break;
            case :
                nLetterValue =@"D";break;
            case :
                nLetterValue =@"E";break;
            case :
                nLetterValue =@"F";break;
            default:nLetterValue=[[NSStringalloc]initWithFormat:@"%lli",ttmpig];

        }
        str = [nLetterValue stringByAppendingString:str];
        if (tmpid == ) {
            break;
        }

    }
    return str;
}

//将16进制的字符串转换成NSData
+ (NSMutableData *)convertHexStrToData:(NSString *)str {
    if (!str || [str length] == ) {
        return nil;
    }

    NSMutableData *hexData = [[NSMutableDataalloc] initWithCapacity:];
    NSRange range;
    if ([str length] % == ) {
        range = NSMakeRange(,);
    } else {
        range = NSMakeRange(,);
    }
    for (NSInteger i = range.location; i < [strlength]; i += ) {
        unsigned int anInt;
        NSString *hexCharStr = [str substringWithRange:range];
        NSScanner *scanner = [[NSScanneralloc] initWithString:hexCharStr];

        [scanner scanHexInt:&anInt];
        NSData *entity = [[NSDataalloc] initWithBytes:&anIntlength:];
        [hexData appendData:entity];

        range.location += range.length;
        range.length = ;
    }

    return hexData;
}

+ (NSString *)convertDataToHexStr:(NSData *)data {
    if (!data || [data length] == ) {
        return @"";
    }
    NSMutableString *string = [[NSMutableStringalloc] initWithCapacity:[datalength]];

    [data enumerateByteRangesUsingBlock:^(constvoid *bytes, NSRange byteRange,BOOL *stop) {
        unsigned char *dataBytes = (unsignedchar*)bytes;
        for (NSInteger i =; i < byteRange.length; i++) {
            NSString *hexStr = [NSStringstringWithFormat:@"%x", (dataBytes[i]) &0xff];
            if ([hexStr length] == ) {
                [string appendString:hexStr];
            } else {
                [string appendFormat:@"0%@", hexStr];
            }
        }
    }];

    return string;
}
//十进制准换为十六进制字符串
+ (NSString *)hexStringFromString:(NSString *)string{
    NSData *myD = [stringdataUsingEncoding:NSUTF8StringEncoding];
    Byte *bytes = (Byte *)[myDbytes];
    //下面是Byte转换为16进制。
    NSString *hexStr=@"";
    for(int i=;i<[myDlength];i++)

    {
        NSString *newHexStr = [NSStringstringWithFormat:@"%x",bytes[i]&0xff];///16进制数

        if([newHexStr length]==)

            hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];

        else

            hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
    }
    return hexStr;
}
+(NSString *) parseByteArray2HexString:(Byte[]) bytes
{
    NSMutableString *hexStr = [[NSMutableString alloc]init];
    int i = ;
    if(bytes)
    {
        while (bytes[i] != '\0')
        {
            NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数
            if([hexByte length]==)
                [hexStr appendFormat:@"0%@", hexByte];
            else
                [hexStr appendFormat:@"%@", hexByte];

            i++;
        }
    }
    NSLog(@"bytes 的16进制数为:%@",hexStr);
    return hexStr;
}