Using RxSwift with StreamChat

Last Edit: May 05 2020

Rx is a generic abstraction of computation expressed through Observable interface. RxSwift is the Swift implementation of Rx.

Stream uses RxSwift to enable easy composition of asynchronous operations and event/data streams. You can check their quick start guide if you're not familiar with RxSwift.

Using RxSwift with StreamChat Swift SDK

By default the official Swift API client handles I/O operation using traditional callback-style. RxSwift is supported by installing our Core library called StreamChatCore. When you use StreamChatCore you can access rx style methods from the client. For instance, Client.shared.addDevice Rx counter part is Client.shared.rx.addDevice.

To use RxSwift, you should have the StreamChatCore dependency installed. If you're using StreamChat, it's already available since StreamChat depends on it. If you're only using StreamChatClient, then you'll need to add StreamChatCore to your Podfile like so:


pod 'StreamChatCore'
                    

In the file you want to use RxSwift,


import StreamChatCore
                    

You can access rx subset as such:


Client.shared.rx.someFunction(arguments)
                    

For example, to add device, you can use both callback way and Rx way:


// Callback way
Client.shared.addDevice(deviceToken: deviceToken)

// Rx way
Client.shared.rx.addDevice(deviceToken: deviceToken).subscribe().disposed(by: disposeBag)


// With completions:
// Callback way
Client.shared.addDevice(deviceToken: deviceToken) { (result) in
    // handle result
}

// Rx way
Client.shared.rx.addDevice(deviceToken: deviceToken).subscribe(onError: { error in
    // handle error
}, onCompleted: {
    // handle completion
}).disposed(by: disposeBag)
                    

As another example, let's look at creating a channel:


let channel = Client.shared.channel(type: .messaging, id: "general")

// using callbacks
Client.shared.create(channel: channel) { (result) in
    // handle result
}

// using Rx
Client.shared.rx.create(channel: channel).subscribe(onError: { (error) in
    // handle error
}, onCompleted: {
    // handle completed
}).disposed(by: disposeBag)
                    

Debugging RxSwift

Here's the official Debugging guide.

You can just put .debug("my debug label") to any Observable to enable debug logging.

Example


let subscription = myInterval(.milliseconds(100))
    .debug("my probe")
    .map { e in
        return "This is simply \(e)"
    }
    .subscribe(onNext: { n in
        print(n)
    })

Thread.sleepForTimeInterval(0.5)

subscription.dispose()
                    

will print


[my probe] subscribed
Subscribed
[my probe] -> Event next(Box(0))
This is simply 0
[my probe] -> Event next(Box(1))
This is simply 1
[my probe] -> Event next(Box(2))
This is simply 2
[my probe] -> Event next(Box(3))
This is simply 3
[my probe] -> Event next(Box(4))
This is simply 4
[my probe] dispose
Disposed