如何从亚马逊SNS主题取消订阅iOS设备？

我正在使用Amazon Web Services的简单通知服务(SNS)开发iOS应用程序.此时,应用程序将设备注册到主题,并可以接收推送通知,这些通知将发布到主题.可以将设备订阅到许多主题.

现在我正在尝试从特定主题取消订阅设备,但SNSUnsubscribeRequest需要SubscriptionARN.我试图从设备中使用EndpointARN,但似乎我要为EndpointARN和TopicARN的组合使用额外的SubscriptionARN.我如何获得此ARN？

在这篇文章中：How do you get the arn of a subscription?他们要求提供整个订阅者列表,并将每个EndpointARN与设备的EndpointARN进行比较.这不可能是我想的正确方法.

订阅主题

// Check if endpoint exist
if (endpointARN == nil) {
    dispatch_async(dispatch_get_main_queue(),^{
        [[self universalAlertsWithTitle:@"endpointARN not found!" andMessage:@"Please create an endpoint for this device before subscribe to topic"] show];
    });
    return NO;
}

// Create topic if not exist
NSString *topicARN = [self findTopicARNFor:topic];
if (!topicARN) {
    [self createTopic:topic];
    topicARN = [self findTopicARNFor:topic];
}

// Subscribe to topic if exist
if (topicARN) {
    SNSSubscribeRequest *subscribeRequest = [[SNSSubscribeRequest alloc] initWithTopicArn:topicARN andProtocol:@"application" andEndpoint:endpointARN];
    SNSSubscribeResponse *subscribeResponse = [snsClient subscribe:subscribeRequest];
    if (subscribeResponse.error != nil) {
        NSLog(@"Error: %@",subscribeResponse.error);
        dispatch_async(dispatch_get_main_queue(),^{
            [[self universalAlertsWithTitle:@"Subscription Error" andMessage:subscribeResponse.error.userInfo.description] show];
        });
        return NO;
    }
}
return YES;

findTopicARNForTopic方法已遍历主题列表,并将后缀与主题名称进行比较.我真的不知道这是不是最好的做法.

取消订阅主题

NSString *topicARN = [self findTopicARNFor:topic];
if (topicARN) {
    SNSUnsubscribeRequest *unsubscribeRequest = [[SNSUnsubscribeRequest alloc] initWithSubscriptionArn:topicARN];
    SNSUnsubscribeResponse *unsubscribeResponse = [snsClient unsubscribe:unsubscribeRequest];
    if (unsubscribeResponse.error) {
        NSLog(@"Error: %@",unsubscribeResponse.error);
    }
}

解决方法

现在我要求整个订户列表并将EndpointARN与设备的EndpointARN进行比较.使用以下方法我得到订阅arn：

- (NSString *)findSubscriptionARNForTopicARN:(NSString *)topicARN
{
    // Iterate over each subscription arn list for a topic arn
    NSString *nextToken = nil;
    do {
        SNSListSubscriptionsByTopicRequest *listSubscriptionRequest = [[SNSListSubscriptionsByTopicRequest alloc] initWithTopicArn:topicARN];
        SNSListSubscriptionsByTopicResponse *response = [snsClient listSubscriptionsByTopic:listSubscriptionRequest];
        if (response.error) {
            NSLog(@"Error: %@",response.error);
            return nil;
        }

        // Compare endpoint arn of subscription arn with endpoint arn of this device
        for (SNSSubscription *subscription in response.subscriptions) {
            if ([subscription.endpoint isEqualToString:endpointARN]) {
                return subscription.subscriptionArn;
            }
        }
        nextToken = response.nextToken;
    } while (nextToken != nil);
    return nil;
}

并使用此方法我从主题中删除设备：

- (void)unsubscribeDeviceFromTopic:(NSString *)topic
{
    NSString *subscriptionARN = [self findSubscriptionARNForTopic:topic];
    if (subscriptionARN) {
        SNSUnsubscribeRequest *unsubscribeRequest = [[SNSUnsubscribeRequest alloc] initWithSubscriptionArn:subscriptionARN];
        SNSUnsubscribeResponse *unsubscribeResponse = [snsClient unsubscribe:unsubscribeRequest];
        if (unsubscribeResponse.error) {
            NSLog(@"Error: %@",unsubscribeResponse.error);
        }
    }
}