# SwiftUI

> Source: `src/content/docs/clients/swiftui.mdx`
> Canonical URL: https://rivet.dev/docs/clients/swiftui
> Description: Build SwiftUI apps with Rivet Actors.

---
## Install

Add the Swift package dependency and import `RivetKitSwiftUI`:

```swift
// Package.swift
dependencies: [
    .package(url: "https://github.com/rivet-dev/rivetkit-swift", from: "2.0.0")
]

targets: [
    .target(
        name: "MyApp",
        dependencies: [
            .product(name: "RivetKitSwiftUI", package: "rivetkit-swift")
        ]
    )
]
```

`RivetKitSwiftUI` re-exports `RivetKitClient` and `SwiftUI`, so a single import covers both.

## Minimal Client

```swift HelloWorldApp.swift
import RivetKitSwiftUI
import SwiftUI

@main
struct HelloWorldApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
                .rivetKit(endpoint: "https://my-namespace:pk_...@api.rivet.dev")
        }
    }
}
```

```swift ContentView.swift
import RivetKitSwiftUI
import SwiftUI

struct ContentView: View {
    @Actor("counter", key: ["my-counter"]) private var counter
    @State private var count = 0

    var body: some View {
        VStack(spacing: 16) {
            Text("\(count)")
                .font(.system(size: 64, weight: .bold, design: .rounded))

            Button("Increment") {
                counter.send("increment", 1)
            }
            .disabled(!counter.isConnected)
        }
        .task {
            count = (try? await counter.action("getCount")) ?? 0
        }
        .onActorEvent(counter, "newCount") { (newCount: Int) in
            count = newCount
        }
    }
}
```

## Actor Options

The `@Actor` property wrapper always uses get-or-create semantics and accepts:

- `name` (required)
- `key` as `String` or `[String]` (required)
- `params` (optional connection parameters)
- `createWithInput` (optional creation input)
- `createInRegion` (optional creation hint)
- `enabled` (toggle connection lifecycle)

```swift
import RivetKitSwiftUI
import SwiftUI

struct ConnParams: Encodable {
    let authToken: String
}

struct ChatView: View {
    @Actor(
        "chatRoom",
        key: ["general"],
        params: ConnParams(authToken: "jwt-token"),
        enabled: true
    ) private var chat

    var body: some View {
        Text("Chat: \(chat.connStatus.rawValue)")
    }
}
```

## Actions

```swift
import RivetKitSwiftUI
import SwiftUI

struct CounterView: View {
    @Actor("counter", key: ["my-counter"]) private var counter
    @State private var count = 0
    @State private var name = ""

    var body: some View {
        VStack {
            Text("Count: \(count)")
            Text("Name: \(name)")

            Button("Fetch") {
                Task {
                    count = try await counter.action("getCount")
                    name = try await counter.action("rename", "new-name")
                }
            }

            Button("Increment") {
                counter.send("increment", 1)
            }
        }
    }
}
```

## Subscribing to Events

```swift
import RivetKitSwiftUI
import SwiftUI

struct GameView: View {
    @Actor("game", key: ["game-1"]) private var game
    @State private var count = 0
    @State private var isGameOver = false

    var body: some View {
        VStack {
            Text("Count: \(count)")
            if isGameOver {
                Text("Game Over!")
            }
        }
        .onActorEvent(game, "newCount") { (newCount: Int) in
            count = newCount
        }
        .onActorEvent(game, "gameOver") {
            isGameOver = true
        }
    }
}
```

## Async Event Streams

```swift
import RivetKitSwiftUI
import SwiftUI

struct ChatView: View {
    @Actor("chatRoom", key: ["general"]) private var chat
    @State private var messages: [String] = []

    var body: some View {
        List(messages, id: \.self) { message in
            Text(message)
        }
        .task {
            for await message in chat.events("message", as: String.self) {
                messages.append(message)
            }
        }
    }
}
```

## Connection Status

```swift
import RivetKitSwiftUI
import SwiftUI

struct StatusView: View {
    @Actor("counter", key: ["my-counter"]) private var counter
    @State private var count = 0

    var body: some View {
        VStack {
            Text("Status: \(counter.connStatus.rawValue)")

            if counter.connStatus == .connected {
                Text("Connected!")
                    .foregroundStyle(.green)
            }

            Button("Fetch via Handle") {
                Task {
                    if let handle = counter.handle {
                        count = try await handle.action("getCount", as: Int.self)
                    }
                }
            }
            .disabled(!counter.isConnected)
        }
    }
}
```

## Error Handling

```swift
import RivetKitSwiftUI
import SwiftUI

struct UserView: View {
    @Actor("user", key: ["user-123"]) private var user
    @State private var errorMessage: String?
    @State private var username = ""

    var body: some View {
        VStack {
            TextField("Username", text: $username)

            Button("Update Username") {
                Task {
                    do {
                        let _: String = try await user.action("updateUsername", username)
                    } catch let error as ActorError {
                        errorMessage = "\(error.code): \(String(describing: error.metadata))"
                    }
                }
            }

            if let errorMessage {
                Text(errorMessage)
                    .foregroundStyle(.red)
            }
        }
        .onActorError(user) { error in
            errorMessage = "\(error.group).\(error.code): \(error.message)"
        }
    }
}
```

## Concepts

### Keys

Keys uniquely identify actor instances. Use compound keys (arrays) for hierarchical addressing:

```swift
import RivetKitSwiftUI
import SwiftUI

struct OrgChatView: View {
    @Actor("chatRoom", key: ["org-acme", "general"]) private var room

    var body: some View {
        Text("Room: \(room.connStatus.rawValue)")
    }
}
```

Don't build keys with string interpolation like `"org:\(userId)"` when `userId` contains user data. Use arrays instead to prevent key injection attacks.

### Environment Configuration

Call `.rivetKit(endpoint:)` or `.rivetKit(client:)` once at the root of your view tree:

```swift
// With endpoint string (recommended for most apps)
@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
                .rivetKit(endpoint: "https://my-namespace:pk_...@api.rivet.dev")
        }
    }
}

// With custom client (for advanced configuration)
@main
struct MyApp: App {
    private let client = RivetKitClient(
        config: try! ClientConfig(endpoint: "https://api.rivet.dev", token: "pk_...")
    )

    var body: some Scene {
        WindowGroup {
            ContentView()
                .rivetKit(client: client)
        }
    }
}
```

When using `.rivetKit(endpoint:)`, the client is created once and cached per endpoint. When using `.rivetKit(client:)`, store the client as a property on `App` (not inside `body`) since SwiftUI can call `body` multiple times.

### Environment Variables

`ClientConfig` reads optional values from environment variables:

- `RIVET_NAMESPACE` - Namespace (can also be in endpoint URL)
- `RIVET_TOKEN` - Authentication token (can also be in endpoint URL)
- `RIVET_RUNNER` - Runner name (defaults to `"default"`)

The endpoint is always required. There is no default endpoint.

### Endpoint Format

Endpoints support URL auth syntax:

```
https://namespace:token@api.rivet.dev
```

You can also pass the endpoint without auth and provide `RIVET_NAMESPACE` and `RIVET_TOKEN` separately. For serverless deployments, set the endpoint to your app's `/api/rivet` URL. See [Endpoints](/docs/general/endpoints#url-auth-syntax) for details.

## API Reference

### Property Wrapper
- `@Actor(name, key:, params:, createWithInput:, createInRegion:, enabled:)` - SwiftUI property wrapper for actor connections

### View Modifiers
- `.rivetKit(endpoint:)` - Configure client with an endpoint URL (creates cached client)
- `.rivetKit(client:)` - Configure client with a custom instance
- `.onActorEvent(actor, event) { ... }` - Subscribe to actor events (supports 0–5 typed args)
- `.onActorError(actor) { error in ... }` - Handle actor errors

### ActorObservable
- `actor.action(name, args..., as:)` - Async action call
- `actor.send(name, args...)` - Fire-and-forget action
- `actor.events(name, as:)` - AsyncStream of typed events
- `actor.connStatus` - Current connection status
- `actor.isConnected` - Whether connected
- `actor.handle` - Underlying `ActorHandle` (optional)
- `actor.connection` - Underlying `ActorConnection` (optional)
- `actor.error` - Most recent error (optional)

### Types
- `ActorConnStatus` - Connection status enum (`.idle`, `.connecting`, `.connected`, `.disconnected`, `.disposed`)
- `ActorError` - Typed actor errors with `group`, `code`, `message`, `metadata`

_Source doc path: /docs/clients/swiftui_
