Chat with iOS and Objective-C
Mario Celi
Ready to implement a chat application using Twilio Programmable Chat Client? Here is how it works at a high level:
- Twilio Programmable Chat is the core product we'll be using to handle all the chat functionality.
- We use a server side app to generate user access tokens which contains all your Twilio account information. The Chat Client uses this token to connect with the API
- Twilio Access Manager is the part of the SDK than handles access tokens and even refreshes them upon token expiration.
For your convenience, we consolidated the source code for this tutorial in a single GitHub repository. Feel free to clone it and tweak as required.
Initialize the Chat Client
The only thing you need to create a client is an access token. This token holds information about your Twilio account and Chat API keys. We have created a web version of Twilio chat in different languages. You can use any of these to generate the token:
We use AFNetworking to make a request to our server and get the access token.
Now it's time to synchronize your Twilio Client.
Synchronize the Chat Client
In the previous step we initialized the Chat client with an Access Manager and set the client's delegate to the shared instance of our MessagingManager.
The synchronizationStatusUpdated delegate method will allow us to know when the client has loaded all the required information. You can change the default initialization values for the client using a TwilioChatClientProperties instance as the options parameter in the previews step.
We need the client to be synchronized before trying to get the channel list. Otherwise, calling client.channelsList() will return nil.
We've initialized the Programmable Chat Client, now lets get a list of channels.
Get the Channel List
Our ChannelManager class takes care of everything related to channels. In the previous step, we waited for the client to synchronize channel information, and assigned an instance of TCHChannelList to our ChannelManager. Now we must get an actual array of channels using the userChannelsWithCompletion and publicChannelsWithCompletion methods.
Let's see how we can listen to events from the chat client so we can update our app's state.
Listen to Client Events
The Chat Client will trigger events such as channelAdded or channelDeleted on our application. Given the creation or deletion of a channel, we'll reload the channel list in the reveal controller. If a channel is deleted and we were currently joined to that channel, the application will automatically join the general channel.
ChannelManager is a TwilioChatClientDelegate. In this class we implement the delegate methods, but we also allow MenuViewController class to be a delegate of ChannelManager, so it can listen to client events too.
Next, we need a default channel.
Join the General Channel
This application will try to join a channel called "General Channel" when it starts. If the channel doesn't exist, it'll create one with that name. The scope of this example application will show you how to work only with public channels, but the Chat client allows you to create private channels and handle invitations.
Once you have joined a channel, you can register a class as the TCHChannelDelegate so you can start listening to events such as messageAdded or memberJoined. We'll show you how to do this in the next step.
Now let's listen for some channel events.
Listen to Channel Events
We registered MainChatViewController as the TCHChannelDelegate, and here we implemented the following methods that listen to channel events:
channelDeleted: When someone deletes a channel.memberJoined: When someone joins the channel.memberLeft: When someone leaves the channel.messageAdded: When someone sends a message to the channel you are connected to.synchronizationStatusChanged: When channel synchronization status changes.
As you may have noticed, each one of these methods include useful objects as parameters. One example is the actual message that was added to the channel.
We've actually got a real chat app going here, but let's make it more interesting with multiple channels.
Join Other Channels
The application uses SWRevealViewController to show a sidebar that contains a list of the channels created for that Twilio account.
When you tap on the name of a channel from the sidebar, that channel is set on the MainChatViewController. The setChannel method takes care of joining to the selected channel and loading the messages.
If we can join other channels, we'll need some way for a super user to create new channels (and delete old ones).
Create a Channel
We use an input dialog so the user can type the name of the new channel. The only restriction here is that the user can't create a channel called "General Channel". Other than that, creating a channel is as simple as calling createChannelWithOptions and passing a dictionary with the new channel information.
Cool, we now know how to create a channel, let's say that we created a lot of channels by mistake. In that case, it would be useful to be able to delete those unnecessary channels. That's our next step!
Delete a Channel
Deleting a channel is easier than creating one. We'll use the UITableView ability to delete a cell. Once you have figured out what channel is meant to be deleted (from the selected cell index path), deleting it is as simple as calling the channel's method destroyWithCompletion.
That's it! We've built an iOS application with Objective-C. Now you are more than prepared to set up your own chat application.
Where to Next?
If you are an iOS developer working with Twilio, you might want to check out this other project:
Twilio Notifications for iOS Quickstart using Swift
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