Get Encoding type of NSData

Question

I have some chunks of data that are encoded with random techniques, say first chunk is encoded by NSUTF8StringEncoding another one with NSASCIIStringEncoding or kCFStringEncodingWindowsArabic.

I don't know which chunk is encoded with which type of encoding. I have tried multiple options e.g. if result is nil then decode with NSNonLossyASCIIStringEncoding, but to no avail. Is there any way to determine a specific chunk of data is encoded with type of Encoding ?

Any help will be appreciated.

That encoding mechanism is broken then. There is no perfect solution to your issue. — trojanfoe, May 24 '16 at 10:55
If you are retrieving data with a WebService, the response headers may give you an hint on the encoding in the "Charset" value. — Larme, May 24 '16 at 12:05
@Larme Good suggestion but I am not retrieving data from WebService. — Muhammad Burhan, May 24 '16 at 12:22
I'm afraid that you may then have to test all the encodings, and find a way to qualify one as the correct one. — Larme, May 24 '16 at 12:23

score 0 · Answer 1 · edited May 23 '17 at 10:28

You can find the answer for your question here: https://stackoverflow.com/a/9836989/2923506

This is a copy&paste code adapted to ARC of the user MiiChiel, because it's a good answer. "if ASCII and UTF8 give both a string in return. For instance: UTF8 gives me some extra characters (negative result) and ASCII are showing the right characters (positive result)."

NSString *responseString, *responseStringASCII, *responseStringUTF8;

responseStringASCII = [[NSString alloc] initWithData:responseData encoding:NSASCIIStringEncoding]; 
if (!responseStringASCII)
{
   // ASCII is not working, will try utf-8!

    responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
}
else
{
    //  ASCII is working, but check if UTF8 gives less characters

    responseStringUTF8  = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];

    if(responseStringUTF8 != nil && [responseStringUTF8 length] < [responseStringASCII length])
    {
        responseString  =   [responseStringUTF8 retain];
    }
    else 
    {
        responseString  =   [responseStringASCII retain];
    }

}

I hope this can help you.

I already checked that, there are number of Encodings out there what do you think is it feasible solution ? — Muhammad Burhan, May 24 '16 at 11:01
Got it. I would say there is a heuristic answer for your question but I don't think there is a unflawed solution. — J. Lopes, May 24 '16 at 11:05
Let's hope I get what I want or I will have to write a very lengthy script :( — Muhammad Burhan, May 24 '16 at 11:12
So if you You can create a category to your object and save the encodetype to it. — J. Lopes, May 24 '16 at 12:33

score 0 · Answer 2 · answered Jul 02 '20 at 14:57

Objective C includes a built-in way to detect a the encoding of a string embedded in NSData.

(Note, if your case you still need to partition each chunk into a separate NSData objects.)

NSData* data = // Assign your NSData object...

NSString* string;
NSStringEncoding encoding = [NSString stringEncodingForData:data encodingOptions:nil convertedString:&string usedLossyConversion:nil];

Get Encoding type of NSData

2 Answers2