gRPCとSwiftによるリアルタイムのアプリやサービスの構築

gRPCとSwiftによるリアルタイムのアプリやサービスの構築

gRPCを使用して、Swiftアプリやバックエンドで魅力的なリアルタイムの体験を構築しましょう。gRPCは、高パフォーマンスの双方向ストリーミングAPI向けに設計されたオープンソースのRPCフレームワークです。Swiftの並行処理で構築された最新型の安全なランタイムを提供する、gRPC Swiftパッケージについて解説します。ワークフローを効率化し、リアルタイム機能を簡単に提供できるようにする、統合されたツールも紹介します。

関連する章
- 0:00 - Introduction
- 1:39 - Meet gRPC
- 2:13 - App overview and demo setup
- 3:30 - Defining the ListRaces RPC
- 4:30 - Setting up Xcode to generate gRPC code
- 7:50 - Managing the gRPC client lifecycle
- 9:36 - Protobuf message format and binary efficiency
- 12:33 - Implementing a bidirectional streaming RPC
- 20:11 - Deploying the service
- 23:11 - Next steps
リソース
関連ビデオ

WWDC25
- Containerizationの紹介
WWDC24
- サーバエコシステムでのSwiftの詳細
WWDC23
- Swift OpenAPI Generatorの紹介

edition = "2024";

import "google/protobuf/timestamp.proto";

service SwiftKartService {
  rpc ListRaces(ListRacesRequest) returns (ListRacesResponse);
}

message ListRacesRequest {
  int32 limit = 1 [default = 100];
}

message ListRacesResponse {
  repeated Race races = 1;
}

message Race {
  string name = 1;
  string location = 2;
  google.protobuf.Timestamp start_time = 3;
  int32 laps = 4;
  string championship = 5;
}

5:55 - grpc-swift-proto-generator-config.json

{
    "generate": {
        "clients": true,
        "servers": false,
        "messages": true
    }
}

6:24 - Add gRPC imports

import GRPCCore
import GRPCNIOTransportHTTP2
import SwiftProtobuf

6:38 - Create a gRPC client connected to a local server

.task {
    do {
        try await withGRPCClient(
            transport: .http2NIOTS(
                address: .ipv4(host: "127.0.0.1", port: 8080),
                transportSecurity: .tls
            )
        ) { client in
            <#code#>
        }
    } catch {
        print("gRPC error: \(error)")
    }
}

7:14 - Call the ListRaces RPC and update the view

.task {
    do {
        try await withGRPCClient(
            transport: .http2NIOTS(
                address: .ipv4(host: "127.0.0.1", port: 8080),
                transportSecurity: .tls
            )
        ) { client in
            let kart = SwiftKartService.Client(wrapping: client)
            let request = ListRacesRequest()
            let response = try await kart.listRaces(request)
            self.races = response.races.map { race in
                RaceInfo(
                    name: race.name,
                    location: race.location,
                    startTime: race.startTime.date,
                    championship: race.championship,
                    laps: Int(race.laps),
                    drivers: race.drivers
                )
            }
        }
    } catch {
        print("gRPC error: \(error)")
    }
}

8:30 - ClientManager.swift

import GRPCCore
import GRPCNIOTransportHTTP2
import Synchronization
import SwiftUI

@Observable
final class ClientManager: Sendable {
    fileprivate let state = Mutex(State.disconnected)

    static func makeTransport() throws -> HTTP2ClientTransport.TransportServices {
        try .http2NIOTS(
            target: .ipv4(address: "127.0.0.1", port: 8080),
            transportSecurity: .plaintext
        )
    }

    func withClient(
        body: (_ client: GRPCClient<HTTP2ClientTransport.TransportServices>) async throws -> Void
    ) async throws {
        let client = try connectIfNecessary()
        try await body(client)
    }

    private func connectIfNecessary() throws -> GRPCClient<HTTP2ClientTransport.TransportServices> {
        try self.state.withLock { state in
            try state.connectIfNecessary()
        }
    }

    func disconnect() {
        let client = self.state.withLock { state in
            state.disconnect()
        }

        client?.beginGracefulShutdown()
    }
}

extension ClientManager {
    enum State {
        case connected(GRPCClient<HTTP2ClientTransport.TransportServices>, Task<Void, any Error>)
        case disconnected
    }
}

extension ClientManager.State {
    mutating func connectIfNecessary() throws -> GRPCClient<HTTP2ClientTransport.TransportServices> {
        switch self {
        case .connected(let client, _):
            return client

        case .disconnected:
            let client = try GRPCClient(transport: ClientManager.makeTransport())
            let task = Task { try await client.runConnections() }
            self = .connected(client, task)
            return client
        }
    }

    mutating func disconnect() -> GRPCClient<HTTP2ClientTransport.TransportServices>? {
        switch self {
        case .connected(let client, _):
            self = .disconnected
            return client
        case .disconnected:
            return nil
        }
    }
}

8:39 - Propagate ClientManager to child views

import SwiftUI

@main
struct SwiftKartApp: App {
    let manager = ClientManager()

    var body: some Scene {
        WindowGroup {
            RaceScheduleView()
                .environment(manager)
        }
    }
}

8:52 - Disconnect ClientManager when the scene enters the background phase

import SwiftUI

@main
struct SwiftKartApp: App {
    let manager = ClientManager()
    @Environment(\.scenePhase) private var scenePhase

    var body: some Scene {
        WindowGroup {
            RaceScheduleView()
                .environment(manager)
        }
        .onChange(of: scenePhase) { _, newPhase in
            switch newPhase {
            case .background :
                manager.disconnect()
            case .inactive, .active:
                break
            @unknown default:
                break
            }
        }
    }
}

9:12 - Inject ClientManager into the view via @Environment
```
@Environment(ClientManager.self) var manager
```

9:21 - Replace withGRPCClient with manager.withClient

.task {
    do {
        try await manager.withClient { client in
            let kart = SwiftKartService.Client(wrapping: client)
            let request = ListRacesRequest()
            let response = try await kart.listRaces(request)
            self.races = response.races.map { race in
                RaceInfo(
                    name: race.name,
                    location: race.location,
                    startTime: race.startTime.date,
                    championship: race.championship,
                    laps: Int(race.laps),
                    drivers: race.drivers
                )
            }
        }
    } catch {
        print("gRPC error: \(error)")
    }
}

9:41 - Using SwiftProtobuf

var race = Race()
race.name = "Duck Pond Dash"
race.location = "Apple Park, Cupertino"
race.startTime = .init(roundingTimeIntervalSince1970: 1_781_198_600)
race.laps = 6
race.championship = "Corporate Cup"
race.drivers = ["Monty", "Pepper", "Mycroft", "Pancakes", "Duke", "Kiko", "Sissi", "Bo"]

try race.serializedBytes()

12:32 - Server

let server = GRPCServer(
    transport: .http2NIOPosix(
        address: .ipv4(host: "127.0.0.1", port: 8080),
        transportSecurity: .plaintext
    ),
    services: [Service()]
)
try await server.serve()

12:45 - Service

struct Service: SwiftKartService.SimpleServiceProtocol {
    private let database = RaceDB()

    func listRaces(
        request: ListRacesRequest,
        context: ServerContext
    ) async throws -> ListRacesResponse {
        var response = ListRacesResponse()
        response.races = await database.listRaces(atMost: request.limit)
        return response
    }
}

13:20 - swift_kart_service.proto

edition = "2024";

import "google/protobuf/duration.proto";
import "google/protobuf/timestamp.proto";

service SwiftKartService {
  rpc ListRaces(ListRacesRequest) returns (ListRacesResponse);
  rpc FollowRace(stream FollowRaceRequest) returns (stream FollowRaceResponse);
}

message ListRacesRequest {
  int32 limit = 1 [default = 100];
}

message ListRacesResponse {
  repeated Race races = 1;
}

message Race {
  string name = 1;
  string location = 2;
  google.protobuf.Timestamp start_time = 3;
  int32 laps = 4;
  string championship = 5;
  repeated string drivers = 6;
}

message FollowRaceRequest {
  string race_name = 1;
  repeated RaceEventType event_types = 2;
}

enum RaceEventType {
  RACE_EVENT_TYPE_UNSPECIFIED = 0;
  RACE_EVENT_TYPE_KART_LOCATIONS = 1;
  RACE_EVENT_TYPE_STANDINGS = 2;
}

message FollowRaceResponse {
  oneof event {
    KartLocations locations = 1;
    Standings standings = 2;
  }
}

message KartLocations {
  message Kart {
    int32 number = 1;
    double latitude = 2;
    double longitude = 3;
    google.protobuf.Timestamp recorded_at = 4;
  }
  repeated Kart karts = 1;
}

message Standings {
  message Entry {
    int32 kart_number = 1;
    google.protobuf.Duration gap_to_leader = 2;
    int32 position = 3;
    int32 lap = 4;
  }

  repeated Entry entries = 1;
}

14:16 - FollowRace stub

func followRace(
    request: RPCAsyncSequence<FollowRaceRequest, any Error>,
    response: RPCWriter<FollowRaceResponse>,
    context: ServerContext
) async throws {
    throw RPCError(code: .unimplemented, message: "FollowRace is unimplemented")
}

14:38 - Implement the FollowRace RPC

func followRace(
    request: RPCAsyncSequence<FollowRaceRequest, any Error>,
    response: RPCWriter<FollowRaceResponse>,
    context: ServerContext
) async throws {
    try await withThrowingTaskGroup { group in
        var iterator = request.makeAsyncIterator()
        guard let first = try await iterator.next() else { return }
        let eventTypes = Mutex(Set(first.eventTypes))

        group.addTask {
            let events = tracker.events(forRace: first.raceName).filter { event in
                eventTypes.withLock { $0.contains(event.type) }
            }

            for await event in events {
                var message = FollowRaceResponse()
                switch event {
                case .locations(let locations):
                    message.locations.karts = locations.map { location in
                        var kart = KartLocations.Kart()
                        kart.number = Int32(location.number)
                        kart.latitude = location.latitude
                        kart.longitude = location.longitude
                        return kart
                    }
                case .standings(let standings):
                    message.standings.entries = standings.map { standing in
                        var entry = Standings.Entry()
                        entry.gapToLeader = .init(rounding: standing.delta, rule: .towardZero)
                        entry.kartNumber = Int32(standing.kartNumber)
                        entry.lap = Int32(standing.lap)
                        entry.position = Int32(standing.position)
                        return entry
                    }
                }

                try await response.write(message)
            }
        }

        while let next = try await iterator.next() {
            eventTypes.withLock { $0 = Set(next.eventTypes) }
        }

        group.cancelAll()
    }
}

16:39 - swift_kart_service.proto

edition = "2024";

import "google/protobuf/duration.proto";
import "google/protobuf/timestamp.proto";

service SwiftKartService {
  rpc ListRaces(ListRacesRequest) returns (ListRacesResponse);
  rpc FollowRace(stream FollowRaceRequest) returns (stream FollowRaceResponse);
}

message ListRacesRequest {
  int32 limit = 1 [default = 100];
}

message ListRacesResponse {
  repeated Race races = 1;
}

message Race {
  string name = 1;
  string location = 2;
  google.protobuf.Timestamp start_time = 3;
  int32 laps = 4;
  string championship = 5;
  repeated string drivers = 6;
}

message FollowRaceRequest {
  string race_name = 1;
  repeated RaceEventType event_types = 2;
}

enum RaceEventType {
  RACE_EVENT_TYPE_UNSPECIFIED = 0;
  RACE_EVENT_TYPE_KART_LOCATIONS = 1;
  RACE_EVENT_TYPE_STANDINGS = 2;
}

message FollowRaceResponse {
  oneof event {
    KartLocations locations = 1;
    Standings standings = 2;
  }
}

message KartLocations {
  message Kart {
    int32 number = 1;
    double latitude = 2;
    double longitude = 3;
    google.protobuf.Timestamp recorded_at = 4;
  }
  repeated Kart karts = 1;
}

message Standings {
  message Entry {
    int32 kart_number = 1;
    google.protobuf.Duration gap_to_leader = 2;
    int32 position = 3;
    int32 lap = 4;
  }

  repeated Entry entries = 1;
}

16:40 - swift_kart_service.proto

edition = "2024";

import "google/protobuf/timestamp.proto";

service SwiftKartService {
  rpc ListRaces(ListRacesRequest) returns (ListRacesResponse);
}

message ListRacesRequest {
  int32 limit = 1 [default = 100];
}

message ListRacesResponse {
  repeated Race races = 1;
}

message Race {
  string name = 1;
  string location = 2;
  google.protobuf.Timestamp start_time = 3;
  int32 laps = 4;
  string championship = 5;
  repeated string drivers = 6;
}

16:56 - Navigation link to LiveStreamView

NavigationLink(destination: LiveStreamView(race: race)) {
    Text("Live stream")
}

17:32 - Call the FollowRace RPC in the LiveStreamView

import SwiftUI
import GRPCCore
import GRPCNIOTransportHTTP2
import SwiftProtobuf

struct LiveStreamView: View {
    private let race: RaceInfo

    @Environment(ClientManager.self) var manager
    @State private var tracking: KartTrackingViewModel
    @State private var standings: [StandingsEntry] = []
    @State private var showLeaderboard = false
    @State private var continuation: AsyncStream<Bool>.Continuation?

    init(race: RaceInfo) {
        self.race = race
        self.tracking = KartTrackingViewModel(race: race)
    }

    var body: some View {
        VStack {
            KartTrackingMapView(viewModel: tracking)
                .ignoresSafeArea()
                .onAppear { tracking.start() }
                .onDisappear { tracking.stop() }
        }
        .onChange(of: showLeaderboard) { _, newValue in
            continuation?.yield(newValue)
        }
        .sheet(isPresented: $showLeaderboard) {
            LeaderboardView(race: race, standings: standings)
                .presentationDetents([.fraction(0.3), .medium, .large])
                .presentationBackgroundInteraction(.enabled)
        }
        .toolbar {
            Toggle(isOn: $showLeaderboard) {
                Label("Leaderboard", systemImage: "list.number")
            }
        }
        .toolbarBackgroundVisibility(.visible, for: .navigationBar)
        .task {
            do {
                let (stream, continuation) = AsyncStream.makeStream(of: Bool.self)
                self.continuation = continuation
                continuation.yield(showLeaderboard)

                try await manager.withClient { client in
                    let kart = SwiftKartService.Client(wrapping: client)
                    try await kart.followRace { requestStream in
                        for await showLeaderboard in stream {
                            var message = FollowRaceRequest()
                            message.raceName = race.name
                            message.eventTypes = [.kartLocations]
                            if showLeaderboard {
                                message.eventTypes.append(.standings)
                            }
                            try await requestStream.write(message)
                        }
                    } onResponse: { responseStream in
                        for try await message in responseStream.messages {
                            if let event = message.event {
                                await handleEvent(event)
                            }
                        }
                    }

                }
            } catch {
                print("gRPC error: \(error)")
            }
        }
    }

    @MainActor
    private func handleEvent(_ event: FollowRaceResponse.OneOf_Event) {
        switch event {
        case .locations(let locations):
            self.tracking.updateKartCoordinates(
                locations.karts.map {
                    TrackedKart(number: $0.number, latitude: $0.latitude, longitude: $0.longitude)
                }
            )
        case .standings(let standings):
            self.standings = standings.entries.map {
                StandingsEntry(
                    kartNumber: $0.kartNumber,
                    secondsToLeader: $0.gapToLeader.timeInterval,
                    position: $0.position,
                    lap: $0.lap
                )
            }
        }
    }
}

#Preview {
    NavigationStack {
        LiveStreamView(race: .example4)
            .environment(ClientManager())
    }
}

20:55 - Containerfile

FROM swift:latest AS builder

# Copy sources into /app
WORKDIR /app
COPY Package.swift Package.resolved .
COPY Sources/ Sources/

# Build the server
RUN swift build -c release --product server
RUN cp "$(swift build -c release --show-bin-path)/server" /usr/bin/server

# Copy the binary from the builder into a smaller runtime image.
FROM swift:slim
COPY --from=builder /usr/bin/server /usr/bin/server

EXPOSE 8080
ENTRYPOINT ["/usr/bin/server"]

21:56 - Deploy service

gcloud run deploy wwdc-demo-server \
  --image us-central1-docker.pkg.dev/wwdc26/wwdc-demo-server/wwdc-demo-server:latest \
  --region us-central1 \
  --use-http2 \
  --allow-unauthenticated

22:22 - Target deployed service

static func makeTransport() throws -> HTTP2ClientTransport.TransportServices {
    try .http2NIOTS(
        target: .dns(host: "wwdc-demo-server-863666503339.us-central1.run.app"),
        transportSecurity: .tls
    )
}

- 0:00 - Introduction
- Why hand-crafting networking code is error-prone, and how generating code from a service specification saves time and eliminates mistakes — setting up gRPC Swift as the approach for real-time experiences.
- 1:39 - Meet gRPC
- gRPC is explained as a CNCF-standard remote procedure call framework that uses Protocol Buffers to define APIs as typed functions rather than HTTP endpoints.
- 2:13 - App overview and demo setup
- A go-karting iOS app demo is introduced, showing how gRPC will replace static mock data with live server-fetched content.
- 3:30 - Defining the ListRaces RPC
- The ListRaces RPC and its request/response messages are defined in a .proto file, covering fields, field numbers, types, and Protobuf Well Known Types.
- 4:30 - Setting up Xcode to generate gRPC code
- The grpc-swift-nio-transport and grpc-swift-protobuf packages are added to the Xcode project, and the GRPCProtobufGenerator build plugin is configured to auto-generate Swift code from the proto file.
- 7:50 - Managing the gRPC client lifecycle
- A shared ClientManager is introduced to reuse connections across views and disconnect the client when the app enters the background, reducing unnecessary latency.
- 9:36 - Protobuf message format and binary efficiency
- The Protobuf binary serialization format is explained — using field numbers instead of names makes messages roughly half the size of equivalent JSON, benefiting mobile apps and service-to-service communication.
- 12:33 - Implementing a bidirectional streaming RPC
- The FollowRace bidirectional streaming RPC is defined, implemented on the Swift server using async sequences and task groups, and wired up in the iOS app to stream live kart positions and standings.
- 20:11 - Deploying the service
- The Swift server is containerised and deployed, then the app is updated to connect over TLS to the live production service.
- 23:11 - Next steps
- Recap of the full gRPC workflow, with pointers to prototype your own integrations, explore the open-source GitHub repository, and contribute to the project.

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関連ビデオ

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WWDC24

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