: selettore non riconosciuto inviato all’istanza

Sto cercando di analizzare un file Json nella vista Tabella e sto ricevendo questo errore

[__NSCFDictionary objectAtIndex:]: selettore non riconosciuto inviato all’istanza e l’app si arresta in modo anomalo. Per favore aiutami, sono nuovo nello sviluppo di iOS.

Il mio codice

@implementation ViewController - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; if (self) { // Custom initialization } return self; } - (void)viewDidLoad { self.title = @"Feeds"; [super viewDidLoad]; [UIApplication sharedApplication].networkActivityIndicatorVisible = YES; NSURL *url = [NSURL URLWithString:@"http://little-people.blogspot.com/feeds/posts /default?alt=json"]; NSURLRequest *request = [NSURLRequest requestWithURL:url]; [[NSURLConnection alloc] initWithRequest:request delegate:self]; } - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { data = [[NSMutableData alloc] init]; NSLog(@"Data Data , %@", data); } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)theData { [data appendData:theData]; } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; feed = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil]; NSLog(@"Data , %@", feed); [mainTableView reloadData]; } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { UIAlertView *errorView = [[UIAlertView alloc] initWithTitle:@"Error" message:@"The download could not complete - please make sure you're connected to either 3G or Wi-Fi." delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil]; [errorView show]; [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; } - (int)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (int)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [feed count]; NSLog(@"Data Data , %@", feed); } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MainCell"]; if(cell == nil){ cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"MainCell"]; } if (([feed count] - 1) >=indexPath.row) { cell.textLabel.text = [[feed objectAtIndex:indexPath.row] objectForKey:@"feed"]; cell.detailTextLabel.text = [[feed objectAtIndex:indexPath.row] objectForKey:@"title"]; } return cell; }