Unescaped control characters in NSJSONSerialization

Question

I have this JSON http://www.progmic.com/ielts/retrive.php that I need to parse. When I do it with NSJSONSerialization, I get "Unescaped control character around character 1981" error.

I need to know:

• What the heck are the unescaped control characters? Is there a list or something?
• How do I get rid of this error? The easiest way?

Thanks in advance.

Answer 1

I added this method to remove the unescaped characters from retrieved string:

- (NSString *)stringByRemovingControlCharacters: (NSString *)inputString 
{ 
    NSCharacterSet *controlChars = [NSCharacterSet controlCharacterSet]; 
    NSRange range = [inputString rangeOfCharacterFromSet:controlChars]; 
    if (range.location != NSNotFound) { 
        NSMutableString *mutable = [NSMutableString stringWithString:inputString]; 
        while (range.location != NSNotFound) { 
            [mutable deleteCharactersInRange:range]; 
            range = [mutable rangeOfCharacterFromSet:controlChars]; 
        } 
        return mutable; 
    } 
    return inputString; 
} 

After recieving the NSData, I convert it to NSString, call the above method to get a new string with removed control characters and then convert the new NSString to NSData again for further processing.

Answer 2

What are you doing before using NSJSONSerialization? Check the encodings, maybe the issue lies there.

I quickly tried and it worked. The source JSON is valid. This is what I got when I serialize the array back to JSON with the pretty print thingy:

[
  {
    "url2": "http://ielts.progmic.com/app/i_COFANewSouthWhales.html",
    "title": "COFA New South Whales ",
    "img": "http://ielts.progmic.com/images/uni/1340407904.jpg",
    "url": "http://ielts.progmic.com/app/COFANewSouthWhales.html",
    "desc": "The College offers nine undergraduate degrees including some double degrees associated with other UNSW faculties.",
    "img2": "http://ielts.progmic.com/images/uni/thumb/1340407904.jpg"
  },
  {
    "url2": "http://ielts.progmic.com/app/i_RoyalCollegeOfArts.html",
    "title": "Royal College Of Arts ",
    "img": "http://ielts.progmic.com/images/uni/1340542224.jpg",
    "url": "http://ielts.progmic.com/app/RoyalCollegeOfArts.html",
    "desc": "The Royal College of Art (informally the RCA) is a public research university specialised in art and design located in London, United Kingdom. It is the world's only wholly postgraduate university of art and design, offering the degrees of Master of Arts (M.A.), Master of Philosophy (M.Phil.) and Doctor of Philosophy (Ph.D.). It was founded in 1837",
    "img2": "http://ielts.progmic.com/images/uni/thumb/1340542224.jpg"
  },
  {
    "url2": "http://ielts.progmic.com/app/i_MIDDLESEXUNIVERSITY.html",
    "title": "MIDDLESEX UNIVERSITY ",
    "img": "http://ielts.progmic.com/images/uni/1340410005.jpg",
    "url": "http://ielts.progmic.com/app/MIDDLESEXUNIVERSITY.html",
    "desc": "We have a reputation for the highest quality teaching, research that makes a real difference to people’s lives and a practical, innovative approach to working with businesses to develop staff potential and provide solutions to business issues. Our expertise is wide ranging, from engineering, information, health and social sciences, to business, arts and education - and we’re national leaders in work based learning solutions.",
    "img2": "http://ielts.progmic.com/images/uni/thumb/1340410005.jpg"
  },
  {
    "url2": "http://ielts.progmic.com/app/i_UNIVERSITYOFSCOTLAND.html",
    "title": "UNIVERSITY OF SCOTLAND ",
    "img": "http://ielts.progmic.com/images/uni/1340410189.jpg",
    "url": "http://ielts.progmic.com/app/UNIVERSITYOFSCOTLAND.html",
    "desc": " Founded in 1451, Glasgow is the fourth-oldest university in the English-speaking world. Over the last five centuries and more, we’ve constantly worked to push the boundaries of what’s possible. We’ve fostered the talents of seven Nobel laureates, one Prime Minister and Scotland’s inaugural First Minister. We’ve welcomed Albert Einstein to give a lecture on the origins of the general theory of relativity. Scotland’s first female graduates completed their degrees here in 1894 and the world’s first ultrasound images of a foetus were published by Glasgow Professor Ian Donald in 1958. In 1840 we became the first university in the UK to appoint a Professor of Engineering, and in 1957, the first in Scotland to have an electronic computer. All of this means that if you choose to work or study here, you’ll be walking in the footsteps of some of the world’s most renowned innovators, from scientist Lord Kelvin and economist Adam Smith, to the pioneer of television John Logie Baird.",
    "img2": "http://ielts.progmic.com/images/uni/thumb/1340410189.jpg"
  }
]

You can copy and paste the JSON in a file, save it in various encodings and see what's going on with your code. UTF-8 should be the way to go.