Objective-C: How to parse NSData? How to break into smaller pieces?

I have the following data inside an NSData object:

<00000000 6f2d840e 31504159 2e535953 2e444446 3031a51b 8801015f
 2d02656e 9f110101 bf0c0cc5 0affff3f 00000003 ffff03>

This data contains information which is marked by tags:

Tag 1 is from byte value 0x84 to 0xa5,

Tag 2 is from byte value 0xa5 to 0x88,

Tag 3 is from byte value 0x88 to 0x5f2d,

Tag 4 is from byte value 0x5f2d to 0x9f11.

How would I go about to get the values of these "tags" from the NSData object?

Regards, EZFrag

I managed a nice solution, deciding to actually use the graymatter

-(int)getIndexOfSubDataInData:(NSData*)haystack forData:(NSData*)needle{
    int dataCounter = 0;
    NSRange dataRange = NSMakeRange(dataCounter, [needle length]);
    NSData* compareData = [haystack subdataWithRange:dataRange];

    while (![compareData isEqualToData:needle]) {

        dataCounter++;
        dataRange = NSMakeRange(dataCounter, [needle length]);
        compareData = [haystack subdataWithRange:dataRange];
    }

    return dataCounter;
}

-(NSData*)getSubDataInData:(NSData*)targetData fromTag:(NSData*)fromTag toTag:(NSData*)toTag{

    int startIndex = [self getIndexOfSubDataInData:targetData forData:fromTag] + [fromTag length];
    int endIndex = [self getIndexOfSubDataInData:targetData forData:toTag];
    int dataLength = endIndex - startIndex;

    NSRange dataRange = NSMakeRange(startIndex, dataLength);

    return [targetData subdataWithRange:dataRange];
}

//here is how I use the code
 NSData* langTagStart=[[NSData alloc] initWithBytes:"\x5F\x2D" length:2];
    NSData* langTagEnd=[[NSData alloc] initWithBytes:"\x9F\x11" length:2];

    NSData* languageData = [self getSubDataInData:[response bytes] fromTag:langTagStart toTag:langTagEnd];

Thanks for your suggestions.

Regards, EZFrag