iPhone xcode array losing state after load

Question

Right i've had a search around and can't find anything.

@synthesize list; // this is an NSArry

-(void) viewDidLoad
{
   NSArray *arr = [self getJSONFeed];
   self.List = [arr retain];     // if i copy the access code into here it works fine.
}

-(void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSUInteger row = [indexPath row];
    NSArray *vals = [list objectAtIndex:row] retain];
    NSString *id = [vals valueForKey:@"id"]; // ERROR
}

right i've taken some of the code to try and provide it as simple as possible, ignore typo's and memory leaks this is sorted.

Basically when I select a row I can't get data out of my 'list' array object. Please can anyone help me out?

Answer 1

Maybe you should try the following (create a temporary array, pass this to the property method and release it afterwards):

 NSArray *arr = [[NSArray alloc] initWithArray:[self getJSONFeed]];
 self.list = arr;
 [arr release];

Make sure you set the property for your NSArray list with (nonatomic, retain) or (nonatomic, copy). Also you have to release the NSArray list in the dealloc method of this class.

Answer 2

Seems like you try to read objects from an array using key-value coding, which will not work (at least it won't do what you expect). If the object you get at that position is really an array, you need to access the elements with objectAtIndex:.

Try setting a breakpoint at the line NSString *id = [vals valueForKey:@"id"]; and inspect vals to see if this object is and contains what you expect.

Answer 3

This is my full code

I'm using http://code.google.com/p/json-framework/ for my JSON connection

my Json is returned in this format:

[
    {
        "id": "7812",
        "title": "title1",
        "fulltext": "main body text",
        "created": "2010-04-06 11:30:03"
    },
    {
        "id": "7813",
        "title": "title2",
        "fulltext": "main body text2",
        "created": "2010-04-06 11:30:03"
    }
]

MainNewsController.h

in here declare:

NSArray *list:

@property (nonatomic, retain) NSArray *list;

MainNewsController.m

@synthesize list;

-(void) viewDidLoad
{
 NSArray *array =  [[NSArray alloc] initWithArray: [self downloadPublicJaikuFeed]];

self.list = array;

NSArray *stream = [list objectAtIndex:6]; // can change index and it's fine

NSString *vall = [stream valueForKey:@"title"]; // works fine

NSString *val1l = [stream valueForKey:@"id"]; // works fine

}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

{

return [self.list count];

}



- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {



    static NSString *MainNewsCellIdentifier = @"MainNewsCellIdentifier";



    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: MainNewsCellIdentifier];

    if (cell == nil) {

        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier: MainNewsCellIdentifier] autorelease];

    }

    NSUInteger row = [indexPath row];

NSDictionary *stream = (NSDictionary *) [list objectAtIndex:row];

cell.textLabel.text = [stream valueForKey:@"id"];

    cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;

    [stream release];

    return cell;

}


#pragma mark -

#pragma mark Table Delegate Methods


- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {



if (childController == nil)

        childController = [[MainNewsDetailController alloc] initWithNibName:@"DisclosureDetail" bundle:nil];



    childController.title = @"News Detail Button Pressed";

NSUInteger row = [indexPath row];

NSArray *stream = (NSArray *) [self.list objectAtIndex:row];

NSString *vall = [stream valueForKey:@"title"]; // error

NSString *val1l = [stream valueForKey:@"id"]; // error

    childController.message = @"111";
    childController.title = @"222";


    [self.navigationController pushViewController:childController animated:YES];


}

Answer 4

Ended up going here http://stackoverflow.com/questions/1438860/nsarray-becomes-nscfarray-when-passed

and found out NSСFArray is subclass of NSMutable Array

so when I changed NSArray List to an NSMutableArray it appears to work.