How do I support offline mode gracefully in Combine with Swift?

To gracefully support offline mode in a Swift application using Combine, you can leverage the built-in features of Combine to handle network requests while also maintaining a local data source. This allows your application to function smoothly even when there is no internet connection. The key is to use a combination of `CurrentValueSubject`, `Publishers`, and `sink` to manage and bind your data effectively.

Example Implementation


        import Combine
        import Foundation

        class DataService {
            private var cancellables = Set()
            private var onlineDataSubject = CurrentValueSubject<[String], Never>([])
            private var offlineData: [String] = []
            private let isConnected = CurrentValueSubject(true)

            init() {
                setupNetworkMonitoring()
            }

            func fetchData() {
                isConnected
                    .combineLatest(onlineDataSubject)
                    .map { isConnected, onlineData in
                        isConnected ? onlineData : self.offlineData
                    }
                    .sink(receiveValue: { data in
                        print("Current Data: \(data)")
                    })
                    .store(in: &cancellables)

                // Simulated network fetch
                fetchOnlineData()
            }

            private func setupNetworkMonitoring() {
                // Simulated network monitoring
                // In a real application, you would use a network monitoring library
                DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                    self.isConnected.send(false) // Simulate Internet Disconnection
                }

                DispatchQueue.main.asyncAfter(deadline: .now() + 10) {
                    self.isConnected.send(true) // Simulate Internet Reconnection
                }
            }

            private func fetchOnlineData() {
                // Simulate a network fetch and updating onlineDataSubject
                DispatchQueue.global().asyncAfter(deadline: .now() + 2) {
                    let fetchedData = ["Data 1", "Data 2", "Data 3"]
                    self.onlineDataSubject.send(fetchedData)
                    self.offlineData = fetchedData // Store for offline use
                }
            }
        }

        // Usage Example
        let dataService = DataService()
        dataService.fetchData()

How do I support offline mode gracefully in Combine with Swift?

Example Implementation

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How do I support offline mode gracefully in Combine with Swift?

Example Implementation

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