How to change an NSString's encoding? - cocoa

Question

I have an NSArray of NStrings, I got this from NSLog when printing the array.
Here is the code I have implemented:
NSMetadataQuery *query = [[NSMetadataQuery alloc] init];
.....
NSArray *queryResults = [[query results] copy];
for (NSMetadataItem *item in queryResults)
{
id value = [item valueForAttribute: kMDItemAlbum];
[databaseArray addObject: value];
}
"The Chronicles Of Narnia: Prince Caspian",
"Taste the First Love",
"Once (Original Soundtrack)",
"430 West Presents Detroit Calling",
"O\U0308\U00d0\U00b9u\U0301\U00b0\U00aeA\U0300O\U0308A\U0300O\U0308I\U0301A\U030a-O\U0301a\U0300A\U0302\U00a1",
"\U7ea2\U96e8\U6d41\U884c\U7f51",
"I\U0300\U00ab\U00bc\U00abO\U0303A\U030aE\U0300y\U0301\U00b7a\U0301",
"A\U0303n\U0303\U00b8e\U0300\U00b2I\U0300C\U0327U\U0300",
"\U00bb\U00b3A\U0308i\U0302O\U0303\U00bdO\U0301N\U0303",
"American IV (The Man Comes Aro",
"All That We Needed",
Now how can I change the human-unreadable strings to human-readable strings? Thanks.

Answer 1

Looking past the escaping done by description (e.g., \U0308), the strings are wrong (e.g., “Öйú°®ÀÖÀÖÍÅ-Óà¡”) because the data you got was wrong.
That's probably not Spotlight's fault. (You could verify that by trying a different ID3-tag library.) Most probably, the files themselves contain poorly-encoded tags.
To fix this:
Encode it in the 8-bit encoding that matches the characters. You can't just pick an encoding (like “ASCII”, which Cocoa mapped to ISO Latin 1 the last time I checked) at random; you need to use the encoding that contains all of the characters in the input and encodes them correctly for what you're going to do next. Try ISO Latin 1, ISO Latin 9, Windows codepage 1252, and MacRoman, in that order.
Decode the encoded data as UTF-8. If this fails, go back to step 1 and try a different encoding.
If step 2 succeeds on any attempt, that is your valid data (unless you're very unlucky). If it fails on all attempts, the data is unrecoverable and you may want to warn the user that their input files contain bogus tags.

Answer 2

Parsing these kind of strings aren't particularly easy: See this SO post for background. It's got links to other SO posts with specific ways of handling this problem.

Answer 3

These strings are utf-8 encoded. You can decode them by:
NSString *myDecoded = [NSString stringWithUTF8String:myEscapedString];
So to process your complete array 'completeArray' you can convert to a const char* first and then back into NSString:
NSMutableArray *processed = [NSMutableArray arrayWithCapacity:completeArray.count];
for (NSString* s in completeArray) {
[processed addObject:[NSString stringWithUTF8String:[s cStringUsingEncoding:ASCIIEncoding]]];
}