更新 ACAccountStoreRequestAccessCompletionHandler for Twitter 中的按钮时出现 iOS 滞后

Question

我正在尝试制作一个切换按钮来指示分享到 Twitter，就像在拍照后出现的 Instagram 分享页面中一样。具体来说，它是一个以 Normal 状态开始的 UIButton，然后在按下时进入 Selected 状态，并以用户的 Twitter 句柄作为标题。

在第一次点击时，它会检查 ACAccountStore 以查找存储的 Twitter 帐户。问题是 requestAccessToAccountsWithType 函数中 ACAccountStoreRequestAccessCompletionHandler 的延迟。在处理程序中，我进行更改以设置 Twitter 句柄并选择按钮。但是，按钮需要很长时间才能在视觉上改变选中状态。尽管它在调用后由 NSLog 验证处于选定状态。

我无法弄清楚是什么导致了这种滞后。这是处理按钮的代码。

- (IBAction)pressedTwitter:(id)sender {
    UIButton *button = (UIButton*)sender;
    if (button.selected) {
        button.selected = !button.selected;
    } else {
        if (self.twitterAccount != nil) {
            button.selected = !button.selected;
        } else {
            [self getTwitterAccount:button];
        }
    }
}


- (void)getTwitterAccount:(UIButton*)button
{
    // Get Account
    ACAccountStore *store = [[ACAccountStore alloc] init];
    ACAccountType *twitterAccountType = [store accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];

    //  Request permission from the user to access the available Twitter accounts
    [store requestAccessToAccountsWithType:twitterAccountType options:nil completion:^(BOOL granted, NSError *error) {
        if (granted) {
            NSArray *twitterAccounts = [store accountsWithAccountType:twitterAccountType];

            if ([twitterAccounts count] > 0) {
                self.twitterAccount = [twitterAccounts objectAtIndex:0];
                [self.twitterButton setTitle:self.twitterAccount.username forState:UIControlStateSelected];


                [self setTwitterButtonNormalText:YES];
                self.twitterButton.selected = YES;
                NSLog(@"Twitter Button Selected");

                self.statusLabel.text = @"Twitter Account Found";
            } else {
                [self setTwitterButtonNormalText:NO];
                button.selected = NO;

                NSLog(@"Not enough Twitter Accounts");
            }
        } else {
            NSLog(@"Twitter Account Permission Not Granted");

            [self setTwitterButtonNormalText:NO];
            button.selected = NO;

        }
    }];
}

- (void)setTwitterButtonNormalText:(BOOL)accountAvailable
{
    if (accountAvailable) {
        [self.twitterButton setTitle:@"Twitter" forState:UIControlStateNormal];
        [self.twitterButton setTitleColor:[UIColor colorWithWhite:0.5 alpha:1.0] forState:UIControlStateNormal];
    } else {
        [self.twitterButton setTitle:@"No Twitter" forState:UIControlStateNormal];
        [self.twitterButton setTitleColor:[UIColor colorWithRed:125./255. green:21./255. blue:0 alpha:1] forState:UIControlStateNormal];
    }
}

感谢您提供的任何帮助。

Answer 1

我刚刚解决了一个类似的问题。这是因为 requestAccessToAccountsWithType 完成函数在不同的线程上，如果你想处理接口(interface)，你必须回到主线程。

可以回到主线程:

dispatch_sync(dispatch_get_main_queue(), ^{
    // code that change the ui, perfom segues, ...
});

试试这个:

- (void)getTwitterAccount:(UIButton*)button
{
    // Get Account
    ACAccountStore *store = [[ACAccountStore alloc] init];
    ACAccountType *twitterAccountType = [store accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];

    //  Request permission from the user to access the available Twitter accounts
    [store requestAccessToAccountsWithType:twitterAccountType options:nil completion:^(BOOL granted, NSError *error) {
        if (granted) {
            NSArray *twitterAccounts = [store accountsWithAccountType:twitterAccountType];

            if ([twitterAccounts count] > 0) {
                self.twitterAccount = [twitterAccounts objectAtIndex:0];
                // go back to the main thread
                dispatch_sync(dispatch_get_main_queue(), ^{
                    [self.twitterButton setTitle:self.twitterAccount.username forState:UIControlStateSelected];
                    [self setTwitterButtonNormalText:YES];
                    self.twitterButton.selected = YES;
                });
                NSLog(@"Twitter Button Selected");

                self.statusLabel.text = @"Twitter Account Found";
            } else {
                // go back to the main thread
                dispatch_sync(dispatch_get_main_queue(), ^{
                    [self setTwitterButtonNormalText:NO];
                    button.selected = NO;
                });
                NSLog(@"Not enough Twitter Accounts");
            }
        } else {
            NSLog(@"Twitter Account Permission Not Granted");
            // go back to the main thread
            dispatch_sync(dispatch_get_main_queue(), ^{
                [self setTwitterButtonNormalText:NO];
                button.selected = NO;
            });
        }
    }];
}