Does a NSURLConnection retain its delegate?


Does a NSURLConnection retain its delegate?



Summary of my question: Does NSURLConnection retain its delegate?

Detailed question and scenario:

I have a custom class, called JsonDownloader that is takes in a URL and returns an NSDictionary of the JSON that the URL returns.

On an iPhone app, I do something like this. (the init method kicks off the whole process)

- (void)viewDidLoad {     JsonDownloder *temp = [[[JsonDownloader alloc] initWithURL:urlString returnDataTo:self]];     [temp release];     [super viewDidLoad]; } 

When the JsonDownloader is done downloading and parsing, it performs a callback to the returnDataTo: object, in this case, the calling object.

This works just fine. Even if I introduce a 30 second delay in my web servers response, the JsonDownloader still exists and does it's callback correctly.

So my questions is this: What is keeping JsonDownloader way past the end of the event cycle? I am explicitly releasing it.

My hunch is that NSURLConnection must do a retain on its delegate, but I didn't see anything in the documentation. Anyone have an ideas?


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1:

Memory Management Question in Objective C
There aren't many setters this don't either copy or retain a variable being passed to it, lest the memory of said variable be re-allocated to any thing else when its retain count reaches zero.. UITableView frame height animation glitch However, the answer is YES, it does. Should a property list be managed by its own model object? A little bit of test code shows the delegate's retain count go up:. How to remove NSString Related Memory Leaks?
NSLog(@"Retain count before: %d", [self retainCount]); NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://google.com"]]; NSURLConnection* conn = [NSURLConnection connectionWithRequest:request delegate:self]; NSLog(@"Retain count after: %d", [self retainCount]); 
which produces in the log:. XCode, iPhone, WebKit Framework - What am I missing?
Running… 2009-07-09 02:13:40.516 delegateRetain[45123:a0f] Retain count before: 1 2009-07-09 02:13:40.525 delegateRetain[45123:a0f] Retain count after: 2  Debugger stopped. What describes NSNumberFormatter -maximumSignificantDigits?
So you must see pretty clearly this in connectionWithRequest:delegate: "self" is indeed having its retain count increased +1. mobile_fu rendering over AJAX so it seems If you're feeling brave and want to mess with the EXC_BAD_ACCESS gods, add in.
[conn dealloc]; NSLog(@"Retain count after dealloc: %d", [self retainCount]); 
which will print out "1" again, showing a post dealloc decrement. However, you'll receive a nice Program received signal: “EXC_BAD_ACCESS”. for the reason this the NSAutoreleasePool will try to release the connection and it will be gone ;).

2:

Most delegate properties are not retained although assigned to prevent circular references. See this question around this as well.. However, NSUrlConnection does not have a specific delegate property. You have to specify the delegate along with the initialization of the connection. I think this is why it does receive a retain, as Dave Martorana showed..

3:

Yes, "The connection retains delegate. It releases delegate when the connection finishes loading, fails, or is canceled," according to the Xcode Documentation for -[NSURLConnection initWithRequest:delegate:] under Special Considerations. See also: NSURLConnection inherent memory leak?.


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