objective c - does not read utf-8 encoded file - objective-c

Question

I'm trying to display some japanese text on the ios simulator and an ipod touch. The text is read from an XML file. The header is:
<?xml version="1.0" encoding="utf-8"?>
When the text is in english, it displays fine. However, when the text is Japanese, it comes out as an unintelligible mishmash of single-byte characters.
I have tried saving the file specifically as unicode using TextEdit. I'm using NSXMLParser to parse the data. Any ideas would be much appreciated.
Here is the parsing code
// Override point for customization after application launch.
NSString *xmlFilePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:#"questionsutf8.xml"];
NSString *xmlFileContents = [NSString stringWithContentsOfFile:xmlFilePath];
NSData *data = [NSData dataWithBytes:[xmlFileContents UTF8String] length:[xmlFileContents lengthOfBytesUsingEncoding: NSUTF8StringEncoding]];
XMLReader *xmlReader = [[XMLReader alloc] init];
[xmlReader parseXMLData: data];

Answer 1

stringWithContentsOfFile: is a deprecated method. It does not do encoding detection unless the file contains the appropriate byte order mark, otherwise it interprets the file as the default C string encoding (the encoding returned by the +defaultCStringEncoding method). Instead, you should use the non-deprecated [and encoding-detecting] method stringWithContentsOfFile:usedEncoding:error:.
You can use it like this:
NSStringEncoding enc;
NSError *error;
NSString *xmlFileContents = [NSString stringWithContentsOfFile:xmlFilePath
usedEncoding:&enc
error:&error];
if (xmlFileContents == nil)
{
NSLog (#"%#", error);
return;
}

Answer 2

First, you should verify with TextWrangler (free from the Mac app store or barebones.com) that your XML file truly is UTF-8 encoded.
Second, try creating xmlFileContents with +stringWithContentsOfFile:encoding:error:, explicitly specifying UTF-8 encoding. Or, even better, bypass the intermediate string entirely, and create data with +dataWithContentsOfFile:.