How to check NSString encode

Question

I read cert info by use

NSString *summary = CFBridgingRelease(SecCertificateCopySubjectSummary(cert));

which get the cert summary, when the summary is chinese, such as 中，the summary return as ä¸

how can i encode ä¸ to 中 correct?

The code how i get cert summary

CFMutableDictionaryRef query = CFDictionaryCreateMutable(nil, 4, nil, nil);
CFDictionaryAddValue(query, kSecClass, kSecClassCertificate);

CFDictionaryAddValue(query, kSecMatchLimit, (const void *)@(100));
CFDictionaryAddValue(query, kSecReturnRef, kCFBooleanTrue);

CFArrayRef items;
OSStatus status = SecItemCopyMatching(query, (CFTypeRef *)&items);
NSArray *certificates = CFBridgingRelease(items);
for (int i = 0; i < certificates.count; i++)
{
    SecCertificateRef certificate = (__bridge SecCertificateRef)certificates[i];
    NSString *summary = (NSString *)CFBridgingRelease(SecCertificateCopySubjectSummary(certificate);
    NSLog(@"%@", summary);
}

when summary is a chinese string, the result is not right.

How did you examine the summary string? Show the code or debugger commands you used to display/print/log it and the exact output. — Ken Thomases
– Ken Thomases, Commented Sep 1, 2017 at 4:54
You're missing a closing parenthesis on the SecCertificateCopySubjectSummary() line, which makes me wonder how this differs from your real code. Anyway, it may be that this is just a bug in SecCertificateCopySubjectSummary(). An NSString or CFString is intended to be encoding-neutral. Or, another way to think about it, it should be already decoded into an internal representation. The API is in terms of "characters", by which it actually means UTF-16 code units, but the internal representation could be anything. It should not be possible to get an encoding mistake like this. — Ken Thomases
– Ken Thomases, Commented Sep 1, 2017 at 8:19
I suppose it's also possible the certificate itself is malformed. For example, it may be that it should use some specific encoding like UTF-8 for its summary, but the data in the certificate is actually using some other encoding. Does it look correct in the Keychain Access utility? — Ken Thomases
– Ken Thomases, Commented Sep 1, 2017 at 8:20
thx for help. finally solve the problem by decode utf8. i post an answer for help others — waitianlou
– waitianlou, Commented Sep 1, 2017 at 8:54

waitianlou · Accepted Answer · 2017-09-01 08:53:42Z

0

Solve the problem. First i print every char in the nsstring, looks like

228 184 173

And chinese character use 3 char in utf8, so i switch it to bin

0b1110 0100
0b10 111000
0b10 101101
//for utf8 to unicode, it's
0100111000101101
//to int
20013
//which is 中 at unicode

And for UTF8 Decoding with NSString help, finally switch the string form utf8 to unicode.

answered Sep 1, 2017 at 8:53

waitianlou

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