FrequentlyAskedQuestions

Frequently Asked Questions

Contents

• Where is the best place to ask questions?
• Where do I raise bug reports or feature requests?
• I get a "Library not loaded" error
• The parser fails to parse string X
• How to get errorTrace from SBJsonParser
• How to get errorTrace when using -[NSString JSONValue]
• My app works in the iOS Simulator, but crashes on the device
• Are there any tutorials?
• Can I link to the framework rather than copy the source into my application?
• Where did the Custom SDK go?
• Will you add support for extension X?
• Are there any alternatives?

Where is the best place to ask questions?

It depends on the question, but the mailing list is probably your best bet. I am not always available and the group has a lot of knowledgeable people that might be able to answer in my place.

Where do I raise bug reports or feature requests?

In the issue tracker. If you provide a patch, or a test, or a good use case, it's much more likely to be fixed/implemented in a timely manner.

I get a "Library not loaded" error

The full error is something like this:

Dyld Error Message:
  Library not loaded: @loader_path/../Frameworks/JSON.framework/Versions/A/JSON
  Referenced from: /Users/santthosh/Library/Application Support/iPhone
Simulator/User/Applications/FC6355D7-960A-4E5F-8003-AA36B561C260/HelloNavigation.app/HelloNavigation
  Reason: image not found

I'm guessing this is this on an iOS device. Dynamic libraries are not supported on iOS. You must link to the libjson target or include the code for the framework directly in your application.

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'";

How to get errorTrace from SBJsonParser

To help you figure out what the error is you may find it handy to use the errorTrace method:

  SBJsonParser *parser = [SBJsonParser new];
  id object = [parser objectWithString:jsonString];
  if (!object)
      NSLog(@"Error trace: %@", parser.errorTrace);

How to get errorTrace when using -[NSString JSONValue]

You're in luck. For versions 2.2 and above the error trace will automatically be printed to the Console log.

My app works in the iOS Simulator, but crashes on the device

You should only encounter this error if you're linking to the static library rather than including the source directly.

The new (3.0) linker apparently has a bug that causes -ObjC to not be processed correctly on device builds. If you have a category in a static library--and try to reference a method in that category--it will work on the simulator but crash on the device.

The solution is to include the linker flag -all_load in addition to -ObjC. If that is not an option, you could try to use the SBJsonParser or SBJsonWriter objects directly rather than the category methods.

(Thanks to Greg Pasquariello)

Are there any tutorials?

Yes! These are all tutorials provided by third-party people:

• JSON Framework for iPhone - a Flickr tutorial in three parts by John Muchow.
• JSON Over HTTP On The iPhone - by Dan Grigsby.
• AS3 to Cocoa touch: JSON by Andy Jacobs.

Can I link to the framework rather than copy the source into my application?

Yes! This is how I use it. Recent versions of Xcode (4.2 and above) have made this much simpler, however this has changed so many times that I do no longer try to document how to do it. Please read the Xcode documentation for your particular version of Xcode for how to do this.

Where did the Custom SDK go?

It was removed in version 2.3 because it was a nightmare to support. Sorry.

Will you add support for extension X?

Probably not. I focus on creating a strict framework. There are, however, several forks that add various features. Maybe one of them adds the feature you want?

See the JSON framework network for a list of such forks.

Are there any alternatives?

Yes, there are. TouchJSON, part of TouchCode is a popular alternative. There's also Yet Another JSON Library which can be used in Objective-C apps.

There's a new kid on the block that promises to be very fast: JSONKit.

Starting in Mac OS X 10.7 and iOS 5, JSON support has been added into Foundation with the NSJSONSerialization class.