[CFDictionary count]: message sent to deallocated instance - iphone

Question

My app is calling the rqst_run method below in didViewLoad method but I've an error. Debugger reports the following error:
[CFDictionary count]: message sent to deallocated instance
and debug marker is placed on this line (in tableView numberOfRowsInSection method below):
if([self.listing_items count] > 0)
I don't know where this variable get released
Declared in header file (interface section):
NSMutableString *rqst_error;
NSMutableData *rqst_data;
NSMutableDictionary *listing_items;
and I defined this method in implementation:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
if([self.listing_items count] > 0)
{
if([self.listing_items objectForKey:#"items"])
{
return [[self.listing_items objectForKey:#"items"] count];
}
}
}
- (void)rqst_run
{
rqst_data = [[NSMutableData data] retain];
NSMutableURLRequest *http_request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:#"http://www.feedserver.com/request/"]];
[http_request setHTTPMethod:#"POST"];
NSString *post_data = [[NSString alloc] initwithFormat:#"param1=%#&param2=%#&param3=%#",rqst_param1,rqst_param2,rqst_param3];
[http_request setHTTPBody:[post_data dataUsingEncoding:NSUTF8StringEncoding]];
rqst_finished = NO;
[post_data release];
NSURLConnection *http_connection = [[NSURLConnection alloc] initWithRequest:http_request];
[http_request release];
if(http_connection)
{
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
if([rqst_data length]>0)
{
NSString *rqst_data_str = [[NSString alloc] rqst_data encoding:NSUTF8StringEncoding];
SBJsonParser *json_parser = [[SBJsonParse alloc] init];
id feed = [json_parser objectWithString:rqst_data_str error:nil];
listing_items = (NSMutableDictionary *)feed;
[json_parser release];
[rqst_data_str release];
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Feed" message:#"No data returned" delegate:self cancemButtonTitle:#"Ok" otherButtonTitles:nil, nil];
[alert show];
[alert release];
}
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Connection Problem" message:#"Connection to server failed" delegate:self cancemButtonTitle:#"Ok" otherButtonTitles:nil, nil];
[alert show];
[alert release];
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[rqst_data setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[rqst_data appendData:data];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
[rqst_data release];
[connection release];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
[rqst_data release];
[connection release];
rqst_finished = YES;
}

Answer 1

NSMutableDictionary must be properly initialized before use. In your code you assign feed to listing_items and then release it. It haven't been retained so listing_items is also removed.
Try to init dictionary like this:
listing_items = [[NSMutableDictionary alloc] initWithDictionary:feed];
and all should work fine.

Answer 2

Instead of this
listing_items = (NSMutableDictionary *)feed;
Use this
self.listing_items = [NSMutableDictionary dictionaryWithDictionary:feed];

Answer 3

It's pretty clear that:
* You use the instance variable instead of the property to assign the value to listing_items
* You put an autoreleased value in this ivar.
listing_items = (NSMutableDictionary *)feed; is clearly your error because feed is an autorleased variable (and then will be deallocated at the end of the current runloop by definition.
Either declare a #property(retain) for listing_items and use it each time you want to assign (autoreleased) value to it (so that the property will manage the retain/release on assignation)
Or retain the stored value manually (but this is painful as you need not to forget to release the previous value before assigning a new one to listing_items each time... which is what the setter method does when called either directly or thru the property assignment)

Answer 4

i think you need to initialize your NSMutableDictionary. Right now its just a pointer pointing to feed. when feed gets released, it just points to nil.
in the viewDidLoad :
listing_items = [[NSMutableDictionary alloc] init];
or you need to retain the data:
listing_items = [(NSMutableDictionary *)feed retain];

Answer 5

SBJsonParser *json_parser = [[SBJsonParse alloc] init];
id feed = [json_parser objectWithString:rqst_data_str error:nil];
listing_items = (NSMutableDictionary *)feed;
[json_parser release];
When you release the json_parser, the dictionary it holds is released too.
So, as others said, you need to retain the dictionary obtained from json_parser.