ios - AFJSONRequestOperation，如果操作成功则更新 UI

Question

我使用 AFNetworking 将数据发送到删除 Web 服务，并使用以下 block :

self.operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {

    [self updateAfterPost];


} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id jsonObject) {
    [handle error]
}];

- (void)updateAfterPost
{
    if ([AppController sharedAppController].currentUser.twitterAccount.crossPost.boolValue == YES) {
        [self postToTwitter];
    }
    [other things that should update the UI]
}

- (void)postToTwitter
{
    ACAccountType *accountType = [self.accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
    [self.accountStore requestAccessToAccountsWithType:accountType options:nil completion:^(BOOL granted, NSError *error) {
        if (granted == YES) {            
            if ([self.twitterAccounts count] > 0) {
                ACAccount *twitterAccount = [self.twitterAccounts objectAtIndex:[AppController sharedAppController].currentUser.twitterAccount.accountId.integerValue];
                NSDictionary *message = @{@"status":self.postTextField.text};
                NSURL *requestURL = [NSURL URLWithString:@"http://api.twitter.com/1/statuses/update.json"];
                SLRequest *postRequest = [SLRequest requestForServiceType:SLServiceTypeTwitter requestMethod:SLRequestMethodPOST URL:requestURL parameters:message];
                postRequest.account = twitterAccount;
                [postRequest performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
                 }];
            }
        }
    }];
}

postToTwitter 操作会导致以下警告(如果我取消注释该方法，则不会发出警告):

Obtaining the web lock from a thread other than the main thread or the web thread. UIKit   should not be called from a secondary thread.

我不知道如何解决这个问题。我在成功 block 中尝试过 NSNotification 但没有运气(通知也可能在后台线程中发送)。有什么想法或建议吗？

更新我也尝试过 [self PerformSelectorOnMainThread:@selector(updateAfterPost) withObject:nil waitUntilDone:YES];。

Answer 1

requestAccessToAccountsWithType 的完成 block 在任意队列上调用，因此您无法在其中调用 UI 元素(您的 postTextField)。

您应该使用dispatch_async调用包装代码:

- (void)postToTwitter
{
    ACAccountType *accountType = [self.accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
    [self.accountStore requestAccessToAccountsWithType:accountType options:nil completion:^(BOOL granted, NSError *error) {
        dispatch_async(dispatch_get_main_queue(), ^{
        if (granted == YES) {            
            if ([self.twitterAccounts count] > 0) {
                ACAccount *twitterAccount = [self.twitterAccounts objectAtIndex:[AppController sharedAppController].currentUser.twitterAccount.accountId.integerValue];
                NSDictionary *message = @{@"status":self.postTextField.text};
                NSURL *requestURL = [NSURL URLWithString:@"http://api.twitter.com/1/statuses/update.json"];
                SLRequest *postRequest = [SLRequest requestForServiceType:SLServiceTypeTwitter requestMethod:SLRequestMethodPOST URL:requestURL parameters:message];
                postRequest.account = twitterAccount;
                [postRequest performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
                 }];
            }
        }
        });  
    }];
}