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June 20, 2023 19:35
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Thread-Safe Network Status Monitor using Swift Actors and Combine
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| // MIT | |
| // by Alexey Grigorev, Ivan Oparin | |
| // A thread-safe service for subscribing to network status updates on Apple's platforms. It | |
| // utilizes Apple's Network framework to monitor network conditions. The service | |
| // uses the actor model for thread safety, protecting from data | |
| // races. Updates are emitted via Combine publishers, for easy integration with | |
| // reactive or async code. Updates include network connection status, if the | |
| // connection is expensive, and if the status has changed." | |
| import Foundation | |
| import Combine | |
| import Network | |
| public struct NetworkStatus: Equatable { | |
| public let connected: Bool? | |
| public let expensive: Bool? | |
| public let wasChanged: Bool? | |
| public init( | |
| connected: Bool? = nil, expensive: Bool? = nil, wasChanged: Bool? = nil | |
| ) { | |
| self.connected = connected | |
| self.expensive = expensive | |
| self.wasChanged = wasChanged | |
| } | |
| } | |
| actor NetworkStatusService: ObservableObject { | |
| private let monitor = NWPathMonitor() | |
| private let queue = DispatchQueue(label: "NetworkStatusService", qos: .default) | |
| private(set) var networkStatus: NetworkStatus = .init() | |
| private let networkSub = CurrentValueSubject<NetworkStatus, Never>(.init()) | |
| public var networkStatusPublisher: AnyPublisher<NetworkStatus, Never> { | |
| networkSub | |
| .removeDuplicates() | |
| .eraseToAnyPublisher() | |
| } | |
| public func start() { | |
| startWatchNetworkCondition() | |
| } | |
| private func startWatchNetworkCondition() { | |
| // let t1 = Date() | |
| monitor.pathUpdateHandler = { [weak self] path in | |
| guard let strongSelf = self else { | |
| return | |
| } | |
| Task { | |
| let prevStatus = await strongSelf.getStatus() | |
| let nextStatus = await strongSelf.buildStatus(path: path, prevStatus: prevStatus) | |
| if prevStatus != nextStatus { | |
| // log network status | |
| } | |
| await strongSelf.updateStatus(newStatus: nextStatus) | |
| strongSelf.networkSub.send(nextStatus) | |
| } | |
| } | |
| monitor.start(queue: queue) | |
| // let t2 = t1.distance(to: Date()) | |
| // log performance | |
| } | |
| private func buildStatus(path: NWPath, prevStatus: NetworkStatus) -> NetworkStatus { | |
| let isExpensive = path.isExpensive | |
| let isConnected = path.status == .satisfied | |
| let wasChanged = prevStatus.connected != isConnected | |
| return .init( | |
| connected: isConnected, | |
| expensive: isExpensive, | |
| wasChanged: wasChanged | |
| ) | |
| } | |
| private func getStatus() -> NetworkStatus { | |
| return networkStatus | |
| } | |
| private func updateStatus(newStatus: NetworkStatus) { | |
| networkStatus = newStatus | |
| } | |
| } |
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