Question

在我的iOS应用程序中，我在Utility类中从Twitter获取推文，然后更新主类UITableView（单元格显示单个推文）。以下是我的代码：

NSMutableArray *tweetsArray = [[NSMutableArray alloc]init];



+ (NSMutableArray *)getTweetStatus:(NSString *)myData{
ACAccountStore *store = [[ACAccountStore alloc] init];
ACAccountType *twitterAccountType = 
[store accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
dispatch_queue_t myCustomQueue;
myCustomQueue = dispatch_queue_create("com.example.MyCustomQueue", NULL);
[store requestAccessToAccountsWithType:twitterAccountType 
                 withCompletionHandler:^(BOOL granted, NSError *error) {
                      dispatch_sync(myCustomQueue, ^{
                     if (!granted) {
                         // The user rejected your request 
                         NSLog(@"User rejected access to the account.");
                     } 
                     else {
                         // Grab the available accounts
                         NSArray *twitterAccounts = 
                         [store accountsWithAccountType:twitterAccountType];

                         if ([twitterAccounts count] > 0) {
                             // Use the first account for simplicity 
                             ACAccount *account = [twitterAccounts objectAtIndex:0];

                             // Now make an authenticated request to our endpoint
                             NSMutableDictionary *params = [[NSMutableDictionary alloc] init];
                             [params setObject:@"1" forKey:@"include_entities"];

                             //  The endpoint that we wish to call
                             NSURL *url =  [NSURL URLWithString:@"http://api.twitter.com/1/statuses/home_timeline.json"];

                             //  Build the request with our parameter 
                             TWRequest *request = 
                             [[TWRequest alloc] initWithURL:url 
                                                 parameters:params 
                                              requestMethod:TWRequestMethodGET];

                             // Attach the account object to this request
                             [request setAccount:account];

                             [request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
                                 dispatch_sync(myCustomQueue, ^{
                                 if (!responseData) {
                                      // inspect the contents of error 
                                      NSLog(@"%@", error);
                                  } 
                                  else {
                                      NSError *jsonError;
                                      NSMutableArray *tweets =[NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableLeaves error:&jsonError];            
                                      if (tweets) {                          
                                          // at this point, we have an object that we can parse
                                          NSLog(@"%@", tweets);
                                      }
                                      else { 
                                          // inspect the contents of jsonError
                                          NSLog(@"%@", jsonError);
                                      }
                                      [tweetsArray addObjectsFromArray:tweets];

                                  }
                                 });
                              }];

                         }
                     }
    });
    }];
     return tweetsArray; 
    }

问题是我不想“返回tweetsArray”，直到我得到响应（即从TWRequest获取响应performRequestWithHandler方法，将tweets响应添加到“tweetsArray”）并为此我在两个地方放置“dispatch_sync” ：

在requestAccessToAccountsWithType:twitterAccountType
在[request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error)

但是我无法做到这一点。

Answer 1

也许您应该将代码更改为以下内容：

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

    // put you twitter request here

    dispatch_async(dispatch_get_main_queue(), ^{

        [self changeMyInterfaceMethod: tweetsArray];

    });
});

在iOS应用程序中从Twitter获取推文时使用dispatch_queue

1 个答案: