iOS NSString stringWithUTF8String / NSString initWithCString wrong utf8 decoding

Question

I'm reading a binary file, with some text fields inside of it.

The original field value is "asdf è" (i cannot change the binary file encoding)

The UTF-8 encoding would be "asdf \xc3\xa8"

What i'm reading is instead "asdf \xc3\x83\xc2\xa8" so the NSString stringWithUTF8String: or initWithCString method gives to me "asdf Ã¨"

How to get back the right "asdf è" value?

thanks

Martin R · Accepted Answer · 2014-07-03 14:22:29Z

2

That is really a strange "encoding" that you read from the binary file.

C3 A8 is the UTF-8 sequence for U+00C3 ("Ã")
C2 A8 it the UTF-8 sequence for U+00A8 ("¨")
The lower bytes of these Unicodes C3 A8 are the UTF-8 sequence for U+00E8 ("è")

The following "trick" uses the ISO Latin 1 encoding to convert the Characters U+00C3 U+00A8 to the bytes C3 A8:

char *s = "\xc3\x83\xc2\xa8";
NSString *s1 = [[NSString alloc] initWithBytes:s length:strlen(s) encoding:NSUTF8StringEncoding];
NSLog(@"%@", s1);   // Ã¨
NSData *d = [s1 dataUsingEncoding:NSISOLatin1StringEncoding];
NSLog(@"%@", d);    // <c3a8>
NSString *s2 = [[NSString alloc] initWithData:d encoding:NSUTF8StringEncoding];
NSLog(@"%@", s2);   // è

answered Jul 3, 2014 at 14:22

Martin R

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