How to convert Hex String to binary data in objective C

Question

I need to convert a Hex String to encoded binary data (not 010101 ), a function equivalent of hex2bin of php http://php.net/manual/en/function.hex2bin.php

I don't need Binary string (e.g 010101), I need something equivalent of php pack function, — user12334
– user12334, Commented Apr 7, 2015 at 6:07

user12334 · Accepted Answer · 2015-09-04 06:47:19Z

I found this through google in case someone is looking:

-(NSData *) CreateDataWithHexString:(NSString *)inputString
{
    NSUInteger inLength = [inputString length];

    unichar *inCharacters = alloca(sizeof(unichar) * inLength);
    [inputString getCharacters:inCharacters range:NSMakeRange(0, inLength)];

    UInt8 *outBytes = malloc(sizeof(UInt8) * ((inLength / 2) + 1));

    NSInteger i, o = 0;
    UInt8 outByte = 0;
    for (i = 0; i < inLength; i++) {
        UInt8 c = inCharacters[i];
        SInt8 value = -1;

        if      (c >= '0' && c <= '9') value =      (c - '0');
        else if (c >= 'A' && c <= 'F') value = 10 + (c - 'A');
        else if (c >= 'a' && c <= 'f') value = 10 + (c - 'a');

        if (value >= 0) {
            if (i % 2 == 1) {
                outBytes[o++] = (outByte << 4) | value;
                outByte = 0;
            } else {
                outByte = value;
            }

        } else {
            if (o != 0) break;
        }
    }

    return [[NSData alloc] initWithBytesNoCopy:outBytes length:o freeWhenDone:YES];
}

Sanjay Mohnani · Accepted Answer · 2015-04-06 10:07:33Z

0

You can do so by-

- (NSString*)convertHexToBinary:(NSString*)hexString 
{
    NSMutableString *returnString = [NSMutableString string];
    for(int i = 0; i < [hexString length]; i++) 
{
        char c = [[hexString lowercaseString] characterAtIndex:i];

        switch(c) {
            case '0': [returnString appendString:@"0000"]; break;
            case '1': [returnString appendString:@"0001"]; break;
            case '2': [returnString appendString:@"0010"]; break;
            case '3': [returnString appendString:@"0011"]; break;
            case '4': [returnString appendString:@"0100"]; break;
            case '5': [returnString appendString:@"0101"]; break;
            case '6': [returnString appendString:@"0110"]; break;
            case '7': [returnString appendString:@"0111"]; break;
            case '8': [returnString appendString:@"1000"]; break;
            case '9': [returnString appendString:@"1001"]; break;
            case 'a': [returnString appendString:@"1010"]; break;
            case 'b': [returnString appendString:@"1011"]; break;
            case 'c': [returnString appendString:@"1100"]; break;
            case 'd': [returnString appendString:@"1101"]; break;
            case 'e': [returnString appendString:@"1110"]; break;
            case 'f': [returnString appendString:@"1111"]; break;
            default : break;
        }
    }

    return returnString;
}

answered Apr 6, 2015 at 10:07

Sanjay Mohnani

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3 Comments

user12334 Over a year ago

This is not what I am looking for Binary data as in content of binary file like "exe"

Vette Over a year ago

It was exactly what "I" was looking for though. Thanks!

Sanjay Mohnani Over a year ago

@Vette Welcome Vette!

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