Question

我正在尝试拉出用户的推文句柄并将其填充到tableview中的文本字段中。请求成功完成并调用执行块，但UI需要几秒钟才能更新。我已经尝试使用NSNotifications来触发UI更改，但是在更新UI时仍然有延迟。下面是我用来从ACAccountStore中提取信息的代码，我用于表的唯一特殊类是自定义UITableViewCell。还有其他人看到这个吗？或者我错过了导致运行时问题的东西？

- (IBAction)connectTwitter:(id)sender {
      UISwitch *sw = (UISwitch *)sender;
      if (sw.isOn == NO) {
           return;
      }    
     ACAccountStore *account = [[ACAccountStore alloc] init];
     ACAccountType *accountType = [account accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
    __weak MBSuitUpViewController *weakSelf = self;
    [account requestAccessToAccountsWithType:accountType options:nil completion:^(BOOL granted, NSError *error) {
        if (granted == YES) {
            NSArray *arrayOfAccounts = [account accountsWithAccountType:accountType];
            if (arrayOfAccounts.count > 0) {
                ACAccount *twitterAccount = [arrayOfAccounts lastObject];
                NSURL *requestURL = [NSURL URLWithString:@"https://api.twitter.com/1/account/verify_credentials.json"];
                SLRequest *user = [SLRequest requestForServiceType:SLServiceTypeTwitter requestMethod:SLRequestMethodGET URL:requestURL parameters:nil];
                user.account = twitterAccount;
                [user performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
                NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:nil];
                    [weakSelf twitterDictionaryHandler:json];
                    weakSelf.userInfo = @{@"name": json[@"name"], @"handle":json[@"screen_name"]};
            }];
            } else {
                UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@"No Twitter Account Found" delegate:nil cancelButtonTitle:nil otherButtonTitles:@"Okay", nil];
                [alert show];
            }
        } else {
            NSLog(@"Permission denied %@", error.localizedDescription);
        }
    }];
}

- (void)twitterDictionaryHandler:(NSDictionary *)dictionary {
    MBSuitUpCell *username = (MBSuitUpCell *)[self.view viewWithTag:2];
    username.textField.text = dictionary[@"screen_name"];
    NSLog(@"Should update textfield");
}

Answer 1

它是否真的立即调用'twitterDictionaryHandler'函数？

如果是这样，但暂时不更新UI那么它似乎是iOS的常见问题。您需要做的是将UI的更改放入GCD（Grand Central Dispatch）主队列，以便它具有优先级并尽快完成。我在下面为其他可能遇到此问题的人举了一个例子。

dispatch_async(dispatch_get_main_queue(), ^{
    username.textField.text = dictionary[@"screen_name"]; 
});

使用twitter句柄执行slrequest performrequestwithhandler stall后，更新uitableviewcell中的文本字段

1 个答案: