Memory leaks or Instruments bad use/misunderstanding?

[vguerci]

Hi,

First of all, thanks a lot for your great work!

Could you please look at that SO question and tell us if those are leaks from JSONKit we are seeing or we are just noobs? :)

Feel free to contact me for more informations.

Vincent.

[vguerci]

That was a bad code + misunderstanding of Instruments reports.

Bad me.

[droppsm]

I'm experiencing the same issue in your SO post - what is the solution? Or are these cached items not a problem?

[vguerci]

The solution is to track and fix the memory leak, 99,94% chances that comes from your code...

[droppsm]

I don't doubt that I'm doing something wrong, I just can't seem to figure out what it is. Are there JSONKit examples somewhere? Was the issue that you had a matter of releasing the decoder object? This is what I am doing...

JSONDecoder *decoder = [JSONDecoder decoder];   
NSDictionary *decodedResponse = [decoder objectWithData:responseData];

Are these autoreleased objects or do I need to handle releasing them? Confused...the leak report looks very similar to the one on Stack Overflow.

Thanks for any help.

[johnezang]

@droppsm,

JSONKit follows the standard Cocoa memory management conventions. In the example you provided, this means that the objects that are returned are autoreleased- you do not and should not send them a release message (unless, of course, you have sent them a retain message).

The most likely cause of your problems is that you have inadvertently sent the decodedResponse object a retain message without a corresponding release (or autorelease) message. If there is no reference to decodedResponse in your applications "live" memory, then there is no way for your application to even know that decodedResponse exists, and therefore it leaks. You will have to track down where the errant retain is, which can sometimes be tricky and non obvious.

[johnezang]

... as for "examples", your snippet of code is pretty much all there is to JSONKit. The only other major function is turning NSDictionary or NSArray objects in to JSON, which is usually done with:

JSONDecoder *decoder = [JSONDecoder decoder];   
NSDictionary *decodedResponse = [decoder objectWithData:responseData];

// Convert decodedResponse back in to JSON...

// UTF8 encoded bytes contained in a NSData object: (fastest)
NSData *convertedBackToJSONUTF8StringData = [decodedResponse JSONData];

// Exactly the same as above, but as a NSString object: (slower)
NSString *convertedBackToJSONString = [decodedResponse JSONString];

That's it. Which one you use depends on your needs- a NSString is easier to manipulate programmatically, and a NSData is usually the best choice when your sending data to a server.

That's all JSONKit does- it converts JSON in to NSDictionary or NSArray objects (via the code you posted), and converts NSDictionary or NSArray objects in to JSON. Everything else is bells and whistles for those that need it.