SKPaymentTransactionObserver方法的UI更新

调用实现SKPaymentTransactionObserver的对象时,我似乎无法更新UI。

- (void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions {

    NSLog(@"paymentQueue: current thread is main thread: %@", [[NSThread currentThread] isMainThread]?@"YES":@"NO");

    for (SKPaymentTransaction *transaction in transactions) {
        if (transaction.transactionState == SKPaymentTransactionStatePurchased) {


            // if the store is still being viewed, update appropriately
            if(spViewController.storeViewController) {
                [spViewController.storeViewController transactionComplete:transaction];
            }
        }
        // other transactionStates omitted for brevity
    }
}

这个 [spViewController.storeViewController transactionComplete:transaction] 执行,但UILabel不显示指定的文本。

- (void) transactionComplete:(SKPaymentTransaction *) transaction {
    NSLog(@"CBTSVC transactionComplete");
    debugLabel.text = @"CBTSVC transactionComplete";

    // other UI updates omitted for brevity
}

当代码执行时,NSLog会将字符串转储到控制台,但UILabel不会更新。我已经确认了对SKPaymentTransactionObserver的回调发生在主线程上,因此UI应该正在更新。(对吗?)

有什么好处?一定少了些简单的东西?

谢谢你的意见和指点。