Checking if a Topic Exists

You can check if a certain topic already exists from your mobile application.

The following example checks if the specified topic already exist in an application scope (you can similarly check the topic existence in a user and group scopes).

Swift:

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

do {
  // Check if the topic exists.
  try topic.checkIfExistsSynchronous()
} catch {
  print("The topic does not exist.")
  return
}

print("The topic already exists.")

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

// Check if the topic exists.
topic.checkIfExists { (topic : KiiSubscribable , isExists : Bool, error : Error?) -> Void in
  if error != nil {
    // Handle the error.
    return
  }
  if (isExists) {
    print("The topic already exists.")
  } else {
    print("The topic does not exist.")
  }
}

Objective-C:

NSError *error = nil;

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

// Check if the topic exists.
BOOL isExists = [topic checkIfExistsSynchronous:&error];

if (error != nil){
  // Handle the error.
  return;
}

if (isExists) {
  NSLog(@"The topic already exists.");
} else {
  NSLog(@"The topic does not exist.");
}

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

// Check if the topic exists.
[topic checkIfExists:^(KiiTopic *aTopic, BOOL isExists, NSError *error) {
  if (error != nil){
    // Handle the error.
    return;
  }

  if (isExists) {
    NSLog(@"The topic already exists.");
  } else {
    NSLog(@"The topic does not exist.");
  }
}];

Here is a description of the sample code:

Instantiates a topic.
Calls the checkIfExistsSynchronous: method to see if the topic is exist or not.