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

Question

我使用一个教程将我的 Twitter 主页包含在我的代码中，但对我来说不起作用。

这是代码

  @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.

它在这里崩溃并出现错误 -[__NSCFDictionary objectAtIndexedSubscript:]: 无法识别的选择器发送到实例

NSDictionary *tweet = _array[indexPath.row];

cell.textLabel.text = tweet[@"text"];

return cell;
     }

Answer 1

问题是 _array 不是数组(它是字典)。

您只需阅读错误消息即可看到这一点。

您不能对 JSONObjectWithData:options:error: 会给您什么样的对象做出任何假设；这取决于 JSON 数据的外观。在这种情况下，JSON 结构导致 Objective-C 等效项成为 NSDictionary。事实上，您可能已经调用您的 array 实例变量 NSArray 没有区别；在 Objective-C 中，对象就是它的本来面目(多态性)。

你没有早点发现问题，因为 count 是 NSDictionary 和 NSArray 的方法，所以当你说 self.array.count 时你没有崩溃>.