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[0]]];
十六进制->十进制
NSString *rechargeInfo =  @"0xff055008";
NSString *cardId2 = [rechargeInfosubstringWithRange:NSMakeRange(2,2)];
cardId2 = [NSStringstringWithFormat:@"%ld",strtoul([cardId2UTF8String],0,16)];


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],0,16);

//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],0,0);

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>9) {
        targetStr=[str substringFromIndex:9];
        
    }
    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=0;i< inter; i++) {
            string = [NSString stringWithFormat:@"0%@",str];
            str = string;
        }
    }
    return string;
}

+(NSString *)stringFromHexString:(NSString *)hexString {//
    
    char *myBuffer = (char *)malloc((int)[hexStringlength] / 2 +1);
    bzero(myBuffer, [hexString length] / 2 + 1);
    for (int i =0; i < [hexString length] - 1; i += 2) {
        unsigned int anInt;
        NSString * hexCharStr = [hexString substringWithRange:NSMakeRange(i, 2)];
        NSScanner * scanner = [[NSScanneralloc] initWithString:hexCharStr] ;
        [scanner scanHexInt:&anInt];
        myBuffer[i / 2] = (char)anInt;
        NSLog(@"myBuffer is %c",myBuffer[i /2] );
    }
    NSString *unicodeString = [NSStringstringWithCString:myBuffer encoding:4];
    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 =0; i<9; i++) {
        ttmpig=tmpid%16;
        tmpid=tmpid/16;
        switch (ttmpig)
        {
            case 10:
                nLetterValue =@"A";break;
            case 11:
                nLetterValue =@"B";break;
            case 12:
                nLetterValue =@"C";break;
            case 13:
                nLetterValue =@"D";break;
            case 14:
                nLetterValue =@"E";break;
            case 15:
                nLetterValue =@"F";break;
            default:nLetterValue=[[NSStringalloc]initWithFormat:@"%lli",ttmpig];
                
        }
        str = [nLetterValue stringByAppendingString:str];
        if (tmpid == 0) {
            break;
        }
        
    }
    return str;
}

//将16进制的字符串转换成NSData
+ (NSMutableData *)convertHexStrToData:(NSString *)str {
    if (!str || [str length] == 0) {
        return nil;
    }
    
    NSMutableData *hexData = [[NSMutableDataalloc] initWithCapacity:8];
    NSRange range;
    if ([str length] %2 == 0) {
        range = NSMakeRange(0,2);
    } else {
        range = NSMakeRange(0,1);
    }
    for (NSInteger i = range.location; i < [strlength]; i += 2) {
        unsigned int anInt;
        NSString *hexCharStr = [str substringWithRange:range];
        NSScanner *scanner = [[NSScanneralloc] initWithString:hexCharStr];
        
        [scanner scanHexInt:&anInt];
        NSData *entity = [[NSDataalloc] initWithBytes:&anIntlength:1];
        [hexData appendData:entity];
        
        range.location += range.length;
        range.length = 2;
    }
  
    return hexData;
}

+ (NSString *)convertDataToHexStr:(NSData *)data {
    if (!data || [data length] == 0) {
        return @"";
    }
    NSMutableString *string = [[NSMutableStringalloc] initWithCapacity:[datalength]];
    
    [data enumerateByteRangesUsingBlock:^(constvoid *bytes, NSRange byteRange,BOOL *stop) {
        unsigned char *dataBytes = (unsignedchar*)bytes;
        for (NSInteger i =0; i < byteRange.length; i++) {
            NSString *hexStr = [NSStringstringWithFormat:@"%x", (dataBytes[i]) &0xff];
            if ([hexStr length] == 2) {
                [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=0;i<[myDlength];i++)
        
    {
        NSString *newHexStr = [NSStringstringWithFormat:@"%x",bytes[i]&0xff];///16进制数
        
        if([newHexStr length]==1)
            
            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 = 0;
    if(bytes)
    {
        while (bytes[i] != '')
        {
            NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数
            if([hexByte length]==1)
                [hexStr appendFormat:@"0%@", hexByte];
            else
                [hexStr appendFormat:@"%@", hexByte];
            
            i++;
        }
    }
    NSLog(@"bytes 的16进制数为:%@",hexStr);
    return hexStr;
}