Proper Encoding for chines character from NSData - iphone

Question

Please help me i'm using below code to get file name.
Here i'm getting NSString from NSData where multipartData is NSMutableArray which contain NSData.
NSString* postInfo = [[NSString alloc] initWithBytes:[[multipartData objectAtIndex:1] bytes] length:[[multipartData objectAtIndex:1] length] encoding:NSUTF8StringEncoding];
I'm getting string like:
Printing description of postInfo:
Content-Disposition: form-data; name="file"; filename="??:??.PNG"
But It should be like:
Printing description of postInfo:
Content-Disposition: form-data; name="file"; filename="华语/華語.PNG"
Thanks in advance.

Answer 1

Obviously the server doesn't encode the response using UTF-8, but probably another Chinese-only encoding. You need to use the Content-Type header to detect which encoding it is, and then find the appropriate NSStringEncoding using the following code;
// set charset to the MIME charset you get from the server
CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding((__bridge CFStringRef)(charset)));
Here is a detailed answer:
// getting the Content-Type header (e.g. "application/json; charset=utf-8")
NSString* header = [[response allHeaderFields] objectForKey:#"Content-Type"];
// getting the MIME type
NSString* charset = nil;
NSArray* contentTypeParts = [header componentsSeparatedByString:#";"];
NSInteger i = 0;
for (NSString* part in contentTypeParts) {
// ignoring first loop (e.g. "application/json")
if (i > 0) {
NSArray* partComponents = [part componentsSeparatedByString:#"="];
if ([partComponents count] == 2 && [#"charset" isEqualToString:[[partComponents objectAtIndex:0] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]]) {
charset = [[partComponents objectAtIndex:1] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
break;
}
}
i++;
}
// converting the MIME type to NSStringEncoding
NSStringEncoding stringEncoding = NSUTF8StringEncoding; // default to UTF8
if (charset) {
stringEncoding = CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding((__bridge CFStringRef)(charset)));
}
// finally you can convert your string properly!
NSString* postInfo = [[NSString alloc] initWithBytes:[[multipartData objectAtIndex:1] bytes] length:[[multipartData objectAtIndex:1] length] encoding:stringEncoding];