Checking the Subscription Status of a Topic

You might want to check if the current user is already subscribed to a topic. For example, your application may want to show a "SUBSCRIBE" button for users who have not yet subscribed to a topic and an "UNSUBSCRIBE" button instead for those users who are already subscribed to the topic.

Here is the sample code for checking the subscription status.

Swift:

// Instantiate the target topic.
let topic = Kii.topic(withName: "SendingAlert")

do{
  // Check if the current user is subscribed to the topic.
  try KiiUser.current()!.pushSubscription().checkIsSubscribedSynchronous(topic)
}catch(let error as NSError){
  print("The current user is not subscribed to the topic.")
  return
}
print("The current user is subscribed to the topic.")

// Instantiate the target topic.
let topic = Kii.topic(withName: "SendingAlert")

// Check if the current user is subscribed to the topic.
KiiUser.current()!.pushSubscription().checkIsSubscribed(topic) { (topic : KiiSubscribable , subscribed : Bool, error : Error?) -> Void in
  if error != nil {
    // Handle the error.
    return
  }
  if (subscribed) {
    print("The current user is subscribed to the topic.")
  } else {
    print("The current user is not subscribed to the topic.")
  }
}

Objective-C:

NSError *error = nil;

// Instantiate the target topic.
KiiTopic *topic = [Kii topicWithName:@"SendingAlert"];

// Check if the current user is subscribed to the topic.
BOOL subscribed = [[KiiUser currentUser].pushSubscription checkIsSubscribedSynchronous:topic
                                                                                 error:&error];
if (subscribed) {
  NSLog(@"The current user is subscribed to the topic.");
} else {
  if (error.kiiHttpStatus == 404) {
    NSLog(@"The current user is not subscribed to the topic.");
  } else {
    // Handle the error.
    return;
  }
}

// Instantiate the target topic.
KiiTopic *topic = [Kii topicWithName:@"SendingAlert"];

// Check if the current user is subscribed to the topic.
[[KiiUser currentUser].pushSubscription checkIsSubscribed:topic
                                                    block:^(id<KiiSubscribable> subscribable, BOOL subscribed, NSError *error) {
  if (subscribed) {
    NSLog(@"The current user is subscribed to the topic.");
  } else {
    if (error.kiiHttpStatus == 404) {
      NSLog(@"The current user is not subscribed to the topic.");
    } else {
      // Handle the error.
      return;
    }
  }
}];

Here is a description of the sample code:

Instantiates a topic.
Calls the checkSubscriptionSynchronous:error: method to see if the current user is already subscribed to the topic.