ios - making accentuated characters to be well displayed in a file path - iphone

Question

I have this code to get all files from a folder :
- (NSMutableArray*) allFilesAtPath:(NSString *)startPath
{
NSMutableArray* listing = [NSMutableArray array];
NSArray* fileNames = [self contentsOfDirectoryAtPath:startPath error:nil];
if (!fileNames) return listing;
for (NSString* file in fileNames) {
NSString* absPath = [startPath stringByAppendingPathComponent:file];
BOOL isDir = NO;
if ([self fileExistsAtPath:absPath isDirectory:&isDir]) {
[listing addObject:absPath];
if (isDir) [listing addObjectsFromArray:[self allFilesAtPath:absPath]];
}
}
return listing;
}
In one test folder, I have a file that is named yahoéo.jpg
When NSLogged, it is displayed as yahoe\U0301o.jpg
Of course, that works fine for any other file without such an accentuated character in the file name.
So, when I try to delete it from the array with :
[theFilesArray removeObject:fileName];
fileName is yahoéo.jpg
it is not remove because it is not found into the array.
Why do I have such a character replacement. I do not find anything in the doc talking about that. Which characters are supposed to have the same treatment ? How should I knew that ?
And most of all, how may I do to get the é character in the files name array ?
EDIT
fileName variable used in the removeObject method is constructed by getting a string from a PList file, and giving it to the following method :
+ (NSString*) fileNameWithString:(NSString*)str
{
NSString* fileName = str;
NSCharacterSet* charactersToRemove = [NSCharacterSet characterSetWithCharactersInString:#".:/\\"];
fileName = [[fileName componentsSeparatedByCharactersInSet:charactersToRemove] componentsJoinedByString:#"#"];
fileName = [fileName stringByAppendingString:#".jpg"];
return fileName;
}

Answer 1

The NSLog output of an NSArray shows all non-ASCII characters in \Unnnn escaped form. But that is only the way NSLog prints it, so that should not be the problem.
I assume that is a problem of "precomposed" vs "decomposed" characters. The HFS filesystem uses decomposed characters in the filenames, so é is stored as two Unicode characters:
U+0065 + U+0301 = "e" + COMBINING ACUTE ACCENT
(and NSLog prints that as e\U0301).
This is different from the single Unicode character (precomposed form)
U+00E9 = "é"
therefore, the string yahoéo.jpg will not be found in the array if its
characters are stored in the precomposed form.
If that is really the problem, you can solve it by
normalizing all file names to either precomposed or decomposed form, using the precomposedStringWithCanonicalMapping or decomposedStringWithCanonicalMapping method of NSString.
Remarks:
Both precomposed and decomposed version of a string will be displayed in the same way (e.g. é).
The compare: method of NSString considers both versions of the string as equal (unless you call it with the NSLiteralSearch option).
The isEqual: method of NSString considers the two versions of the string as different,
and that is used by removeObject: to find the object to remove.