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I have some xml that is coming back from a web service. I in turn use xslt to turn that xml into json (I am turning someone else's xml service into a json-based service). My service, which is now outputting JSON, is consumed by my iphone app using the de facto iphone json framework, SBJSON.

The problem is, using the [string JSONValue] method chokes, and I can see that it's due to line breaks. Lo and behold, even the FAQ tells me the problem but I don't know how to fix it.

The parser fails to parse string X

Are you sure it's legal JSON? This framework is really strict, so won't accept stuff that (apparently) several validators accepts. In particular, literal TAB, NEWLINE or CARRIAGE RETURN (and all other control characters) characters in string tokens are disallowed, but can be very difficult to spot. (These characters are allowed between tokens, of course.)

If you get something like the below (the number may vary) then one of your strings has disallowed Unicode control characters in it.

NSLocalizedDescription = "Unescaped control character '0x9'";

I have tried using a line such as: NSString *myString = [myString stringByReplacingOccurrencesOfString:@"\n" withString:@"\\n"];

But that doesn't work. My xml service is not coming back as CDATA. The xml does have a line break in it as far as I can tell (how would I confirm this). I just want to faithfully transmit the line break into JSON.

I have actually spent an entire day on this, so it's time to ask. I have no pride anymore. Thanks alot

user798719
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3 Answers3

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It sounds like your XSLT is not working, in that it is not producing legal JSON. This is unsurprising, as producing correctly formatted JSON strings is not entirely trivial. I'm wondering if it would be simpler to just use the standard XML library to parse the XML into data structures that your app can consume.

Stig Brautaset
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Escaping a new line character should work. So following line should ideally work. Just check if your input also contains '\r' character. 

 NSString *myString = [myString stringByReplacingOccurrencesOfString:@"\n" withString:@"\\n"];

You can check which control character is present in the string using any editor which supports displaying all characters (non-displayable characters as well). e.g. using Notepad++ you can view all characters contained in a string.

Nilesh
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I don't have a solution for you, but I usually use CJSONSerializer and CJSONDeserializer from the TouchJSON project and it is pretty reliable, I have never had a problem with line breaks before. Just a thought.

http://code.google.com/p/touchcode/source/browse/TouchJSON/Source/JSON/CJSONDeserializer.m?r=6294fcb084a8f174e243a68ccfb7e2c519def219 http://code.google.com/p/touchcode/source/browse/TouchJSON/Source/JSON/CJSONSerializer.m?r=3f52118ae2ff60cc34e31dd36d92610c9dd6c306

Michael Frederick
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