Objective-C: NSString not being entirely decoded from UTF-8

Question

I'm querying a web server which returns a JSON string as NSData . The string is in UTF-8 format so it is converted to an NSString like this.

NSString *receivedString = [[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding]; 

However, some UTF-8 escapes remain in the outputted JSON string which causes my app to behave erratically. Things like \’ remain in the string. I've tried everything to remove them and replace them with their actual characters.

The only thing I can think of is to replace the occurances of UTF-8 escapes with their characters manually, but this is a lot of work if there's a quicker way!

Here's an example of an incorrectly parsed string:

{"title":"The Concept, Framed, The Enquiry, Delilah\u2019s Number 10  ","url":"http://livebrum.co.uk/2012/05/31/the-concept-framed-the-enquiry-delilah\u2019s-number-10","date_range":"31 May 2012","description":"","venue":{"title":"O2 Academy 3 ","url":"http://livebrum.co.uk/venues/o2-academy-3"}

As you can see, the URL hasn't been completely converted.

Thanks,

Answer 1

The \’ syntax isn't part of UTF-8 encoding, it's a piece of JSON-specific syntax. NSString parses UTF-8, not JSON, so doesn't understand it.

You should use NSJSONSerialization to parse the JSON then pull the string you want from the output of that.

So, for example:

NSError *error = nil;
id rootObject = [NSJSONSerialization
                      JSONObjectWithData:receivedData
                      options:0
                      error:&error];

if(error)
{
    // error path here
}

// really you'd validate this properly, but this is just
// an example so I'm going to assume:
//
//    (1) the root object is a dictionary;
//    (2) it has a string in it named 'url'
//
// (technically this code will work not matter what the type
// of the url object as written, but if you carry forward assuming
// a string then you could be in trouble)

NSDictionary *rootDictionary = rootObject;
NSString *url = [rootDictionary objectForKey:@"url"];

NSLog(@"URL was: %@", url);