Subscribing to a Topic

Subscription to a topic is necessary to receive Push to User notifications. Once a user subscribes to a topic, all push messages sent to this topic will be delivered to the user.

The following sample code subscribes to an application-scope topic named SendingAlert.

Swift:

// Instantiate an existing topic in the application scope.
let topicName = "SendingAlert"
let topic = Kii.topic(withName: topicName)

do{
  // Subscribe to the topic.
  try KiiUser.current()!.pushSubscription().subscribeSynchronous(topic)
}catch let error as NSError {
  // Handle the error.
  return
}

// Instantiate an existing topic in the application scope.
let topicName = "SendingAlert"
let topic = Kii.topic(withName: topicName)

// Subscribe to the topic.
KiiUser.current()!.pushSubscription().subscribe(topic) { (subscription : KiiPushSubscription, error : Error?) -> Void in
  if error != nil {
    // Handle the error.
    return
  }
}

Objective-C:

NSError *error = nil;

// Instantiate an existing topic in the application scope.
NSString *topicname = @"SendingAlert";
KiiTopic *topic = [Kii topicWithName:topicname];

// Subscribe to the topic.
KiiPushSubscription *subscription = [[KiiUser currentUser].pushSubscription subscribeSynchronous:topic
                                                                                           error:&error];
if (error != nil) {
  // Handle the error.
  return;
}

// Instantiate an existing topic in the application scope.
NSString *topicname = @"SendingAlert";
KiiTopic *topic = [Kii topicWithName:topicname];

// Subscribe to the topic.
[[KiiUser currentUser].pushSubscription subscribe:topic
                                            block:^(KiiPushSubscription *subscription, NSError *error) {
  if (error != nil) {
    // Handle the error.
    return;
  }
}];

The next sample code subscribes to a group-scope topic named GroupTopic. In this sample code, we are getting the existing topic with its URL.

Swift:

// Instantiate an existing group.
let group = KiiGroup(uri: groupURI)

// Instantiate an existing topic in the group scope.
let topicName = "GroupTopic"
let topic = group.topic(withName: topicName)

do{
  // Subscribe to the topic.
  // (The current user must be a group member)
  try KiiUser.current()!.pushSubscription().subscribeSynchronous(topic)
}catch let error as NSError {
  // Handle the error.
  return
}

// Instantiate an existing group.
let group = KiiGroup(uri: groupURI)

// Instantiate an existing topic in the group scope.
let topicName = "GroupTopic"
let topic = group.topic(withName: topicName)

// Subscribe to the topic.
// (The current user must be a group member)
KiiUser.current()!.pushSubscription().subscribe(topic) { (subscription : KiiPushSubscription, error : Error?) -> Void in
  if error != nil {
    // Handle the error.
    return
  }
}

Objective-C:

NSError *error = nil;

// Instantiate an existing group.
KiiGroup *group = [KiiGroup groupWithURI:groupUri];

// Instantiate an existing topic in the group scope.
NSString *topicname = @"GroupTopic";
KiiTopic *topic = [group topicWithName:topicname];

// Subscribe to the topic.
// (The current user must be a group member)
KiiPushSubscription *subscription = [[KiiUser currentUser].pushSubscription subscribeSynchronous:topic
                                                                                           error:&error];
if (error != nil) {
  // Handle the error.
  return;
}

// Instantiate an existing group.
KiiGroup *group = [KiiGroup groupWithURI:groupUri];

// Instantiate an existing topic in the group scope.
NSString *topicname = @"GroupTopic";
KiiTopic *topic = [group topicWithName:topicname];

// Subscribe to the topic.
// (The current user must be a group member)
[[KiiUser currentUser].pushSubscription subscribe:topic
                                            block:^(KiiPushSubscription *subscription, NSError *error) {
  if (error != nil) {
    // Handle the error.
    return;
  }
}];

The last sample code subscribes to a user-scope topic named MyTODO.

Swift:

// Instantiate an existing topic in the user scope.
let user = KiiUser.current()!
let topicName = "MyTODO"
let topic = user.topic(withName: topicName)

do{
  // Subscribe to the topic.
  try KiiUser.current()!.pushSubscription().subscribeSynchronous(topic)
}catch let error as NSError {
  // Handle the error.
  return
}

// Instantiate an existing topic in the user scope.
let user = KiiUser.current()!
let topicName = "MyTODO"
let topic = user.topic(withName: topicName)

// Subscribe to the topic.
KiiUser.current()!.pushSubscription().subscribe(topic) { (subscription : KiiPushSubscription, error : Error?) -> Void in
  if error != nil {
    // Handle the error.
    return
  }
}

Objective-C:

NSError *error = nil;

// Instantiate an existing topic in the user scope.
KiiUser* user = [KiiUser currentUser];
NSString *topicname = @"MyTODO";
KiiTopic *topic = [user topicWithName:topicname];

// Subscribe to the topic.
[[KiiUser currentUser].pushSubscription subscribeSynchronous:topic
                                                       error:&error];
if (error != nil) {
  // Handle the error.
  return;
}

// Instantiate an existing topic in the user scope.
KiiUser* user = [KiiUser currentUser];
NSString *topicname = @"MyTODO";
KiiTopic *topic = [user topicWithName:topicname];

// Subscribe to the topic.
[[KiiUser currentUser].pushSubscription subscribe:topic
                                            block:^(KiiPushSubscription *subscription, NSError *error) {
  if (error != nil) {
    // Handle the error.
    return;
  }
}];

For all examples, here is a brief description of what is happening in the sample code:

Instantiates a target topic.
Calls the subscribeSynchronous:error: method while specifying the target topic.