-[__NSCFDictionary objectAtIndexedSubscript:]: unrecognized selector sent to instance - ios

Question

I used one tutorial to include My twitter home page in my code, but for me does not works.
This is the code
#implementation VSViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self twitterTimeline];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)twitterTimeline {
ACAccountStore *account = [[ACAccountStore alloc] init]; // Creates AccountStore object.
// Asks for the Twitter accounts configured on the device.
ACAccountType *accountType = [account accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
[account requestAccessToAccountsWithType:accountType options:nil completion:^(BOOL granted, NSError *error)
{
// If we have access to the Twitter accounts configured on the device we will contact the Twitter API.
if (granted == YES){
NSArray *arrayOfAccounts = [account accountsWithAccountType:accountType]; // Retrieves an array of Twitter accounts configured on the device.
// If there is a leat one account we will contact the Twitter API.
if ([arrayOfAccounts count] > 0) {
ACAccount *twitterAccount = [arrayOfAccounts lastObject]; // Sets the last account on the device to the twitterAccount variable.
NSURL *requestAPI = [NSURL URLWithString:#"http://api.twitter.com/1.1/statuses/user_timeline.json"]; // API call that returns entires in a user's timeline.
// The requestAPI requires us to tell it how much data to return so we use a NSDictionary to set the 'count'.
NSMutableDictionary *parameters = [[NSMutableDictionary alloc] init];
[parameters setObject:#"100" forKey:#"count"];
[parameters setObject:#"1" forKey:#"include_entities"];
// This is where we are getting the data using SLRequest.
SLRequest *posts = [SLRequest requestForServiceType:SLServiceTypeTwitter requestMethod:SLRequestMethodGET URL:requestAPI parameters:parameters];
posts.account = twitterAccount;
// The postRequest: method call now accesses the NSData object returned.
[posts performRequestWithHandler:
^(NSData *response, NSHTTPURLResponse
*urlResponse, NSError *error)
{
// The NSJSONSerialization class is then used to parse the data returned and assign it to our array.
self.array = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableLeaves error:&error];
if (self.array.count != 0) {
dispatch_async(dispatch_get_main_queue(), ^{
[self.tableView reloadData]; // Here we tell the table view to reload the data it just recieved.
});
}
}];
}
} else {
// Handle failure to get account access
NSLog(#"%#", [error localizedDescription]);
}
}];
}
#pragma mark Table View Data Source Mehtods
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Returns the number of rows for the table view using the array instance variable.
return [_array count];
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// Creates each cell for the table view.
static NSString *cellID = #"CELLID" ;
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:cellID];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID];
}
// Creates an NSDictionary that holds the user's posts and then loads the data into each cell of the table view.
IT CRASHES HERE with the error -[__NSCFDictionary objectAtIndexedSubscript:]: unrecognized selector sent to instance
NSDictionary *tweet = _array[indexPath.row];
cell.textLabel.text = tweet[#"text"];
return cell;
}

Answer 1

The problem is that _array is not an array (it's a dictionary).
You only have to read the error message to see this.
You can't make any assumptions about what kind of object JSONObjectWithData:options:error: will give you; it depends on what the JSON data looks like. In this case, the JSON structure has resulted in the Objective-C equivalent being an NSDictionary. The fact that you may have called your array instance variable an NSArray makes no difference; in Objective-C, an object is what it is (polymorphism).
You didn't catch the problem earlier because count is a method both of NSDictionary and of NSArray, so you didn't crash when you said self.array.count.