Kotlin Channel Groups API Reference for Realtime Apps

Channel Groups allows PubNub developers to bundle thousands of channels into a group that can be identified by name. These Channel Groups can then be subscribed to, receiving data from the many backend-channels the channel group contains.

Learn more about our Channel Groups here.

Calling Kotlin methods

Most PubNub Kotlin SDK method invocations return an Endpoint object, which allows you to decide whether to perform the operation synchronously or asynchronously. You must choose one of these or the operation will not be performed at all.

For example, the following code is valid and will compile, but the publish won't be performed:

pubnub.publish(
    message = "this sdk rules!",
    channel = "my_channel"
)

To successfully publish a message, you must follow the actual method invocation with whether to perform it synchronously or asynchronously, for example:

pubnub.publish(
    message = "this sdk rules!",
    channel = "my_channel"
).async { result, status ->
    if (status.error) {
        // handle error
    } else {
        // handle successful method result
    }
}

Adding Channels

Requires Stream Controller add-onRequires that the Stream Controller add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

Description

This function adds a channel to a channel group.

Methods

Adding Channels is accomplished by using the following method(s) in the Kotlin SDK:

Note

200 channels can be added to the channel group per API call.

pubnub.addChannelsToChannelGroup(
    channelGroup: String,
    channels: List<String>
).async { result, status -> }

Parameter	Type	Required	Description
`channelGroup`	`String`	Yes	The channel group to add the channels to.
`channels`	`List<String>`	Yes	The channels to add to the channel group.

Basic Usage

pubnub.addChannelsToChannelGroup(
    channelGroup = "cg1"
    channels = listOf("ch1", "ch2", "ch3")
).async { result, status -> }

Response

The addChannelsToChannelGroup() doesn't return actionable data, be sure to check the status object on the outcome of the operation by checking the status.error.

Listing Channels

Description

This function lists all the channels of the channel group.

Methods

Listing channels is accomplished by using the following method(s) in the Kotlin SDK:

pubnub.listChannelsForChannelGroup(
    channelGroup: String
).async { result, status -> }

Parameter	Type	Required	Description
`channelGroup`	`String`	Yes	Channel group to fetch the belonging channels

Basic Usage

pubnub.listChannelsForChannelGroup(
    channelGroup = "cg1"
).async { result, status ->
    if (!status.error) {
        result!!.channels // ["ch1", "ch2", "ch3"]
    } else {
        // handle error
        status.exception?.printStackTrace()
    }
}

Returns

The listChannelsForChannelGroup() operation returns a PNChannelGroupsAllChannelsResult which contains the following operations:

Method	Type	Description
`channels`	`List<String>`	List of `channels` of a `channel group`.

Removing Channels

Description

This function removes the channels from the channel group.

Method(s)

Removing Channels is accomplished by using the following method(s) in the Kotlin SDK:

pubnub.removeChannelsFromChannelGroup(
    channels: List<String>,
    channelGroup: String
).async { result, status -> }

Parameter	Type	Required	Description
`channels`	`List<String>`	Yes	The channels to remove from the channel group
`channelGroup`	`String`	Yes	The channel group to remove channels from

Basic Usage

pubnub.removeChannelsFromChannelGroup(
    channelGroup = "cg1"
).async { result, status -> }

Returns

The removeChannelsFromChannelGroup() doesn't return actionable data, be sure to check the status object on the outcome of the operation by checking the status.error.

Deleting Channel Group

Description

This function removes the channel group.

Method(s)

Deleting Channel Group is accomplished by using the following method(s) in the Kotlin V4 SDK:

pubnub.deleteChannelGroup(
    channelGroup: String
).async { result, status -> }

Parameter	Type	Required	Description
`channelGroup`	`String`	Yes	The channel group to remove

Basic Usage

pubnub.deleteChannelGroup(
    channelGroup = "cg1"
).async { result, status -> }

Returns

The deleteChannelGroup() doesn't return actionable data, be sure to check the status object on the outcome of the operation by checking the status.error.