Migrate to Observable and new #Preview

NAMS/Bluetooth/BluetoothManager.swift

@@ -9,11 +9,12 @@
 import CoreBluetooth
 
 
-class BluetoothManager: NSObject, ObservableObject, CBCentralManagerDelegate {
+@Observable
+class BluetoothManager: NSObject, CBCentralManagerDelegate {
     private let bluetoothManager: CBCentralManager
     private let dispatchQueue: DispatchQueue
 
-    @Published private(set) var bluetoothState: CBManagerState
+    private(set) var bluetoothState: CBManagerState
 
     override init() {
         // We use a separate dispatch queue, be aware that all delegate calls are not getting on the main thread.

NAMS/Contacts/Contacts.swift

@@ -70,9 +70,7 @@ struct Contacts: View {
 
 
 #if DEBUG
-struct Contacts_Previews: PreviewProvider {
-    static var previews: some View {
-        Contacts(presentingAccount: .constant(true))
-    }
+#Preview {
+    Contacts(presentingAccount: .constant(true))
 }
 #endif

NAMS/EEG/EEGChannelMark.swift

@@ -32,12 +32,9 @@ struct EEGChannelMark: ChartContent {
 
 
 #if DEBUG
-struct EEGChannelMark_Previews: PreviewProvider {
-    static let randomSamples = EEGMeasurementGenerator(sampleRate: 60)
-
-    static var previews: some View {
-        let generated = randomSamples.generateRecording(sampleTime: 5, recordingOffset: 10)
-        EEGChart(measurements: generated.data.suffix(from: 0), for: .af7, baseTime: generated.baseTime)
-    }
+#Preview {
+    let randomSamples = EEGMeasurementGenerator(sampleRate: 60)
+    let generated = randomSamples.generateRecording(sampleTime: 5, recordingOffset: 10)
+    return EEGChart(measurements: generated.data.suffix(from: 0), for: .af7, baseTime: generated.baseTime)
 }
 #endif

NAMS/EEG/EEGChart.swift

@@ -81,13 +81,14 @@ struct EEGChart: View {
 
 
 #if DEBUG
-struct EEGChart_Previews: PreviewProvider {
-    static let randomSamples = EEGMeasurementGenerator(sampleRate: 60)
+private let randomSamples = EEGMeasurementGenerator(sampleRate: 60)
+private let generated = randomSamples.generateRecording(sampleTime: 5, recordingOffset: 10)
 
-    static var previews: some View {
-        let generated = randomSamples.generateRecording(sampleTime: 5, recordingOffset: 10)
-        EEGChart(measurements: generated.data.suffix(from: 0), for: .af7, baseTime: generated.baseTime)
-        EEGChart(measurements: generated.data.suffix(from: 0), for: .af8, baseTime: generated.baseTime)
-    }
+#Preview {
+    EEGChart(measurements: generated.data.suffix(from: 0), for: .af7, baseTime: generated.baseTime)
+}
+
+#Preview {
+    EEGChart(measurements: generated.data.suffix(from: 0), for: .af8, baseTime: generated.baseTime)
 }
 #endif

NAMS/EEG/EEGDeviceDetails.swift

@@ -15,7 +15,7 @@ struct EEGDeviceDetails: View {
     @Environment(\.locale)
     private var locale
 
-    @ObservedObject private var device: ConnectedDevice
+    private let device: ConnectedDevice
 
     var body: some View {
         List {
@@ -146,27 +146,21 @@ struct EEGDeviceDetails: View {
 
 
 #if DEBUG
-struct EEGDeviceDetails_Previews: PreviewProvider {
-    @StateObject static var model = EEGViewModel(mock: MockEEGDevice(name: "Mock Device", model: "Mock", state: .connected))
+#Preview {
+    let model = EEGViewModel(mock: MockEEGDevice(name: "Mock Device", model: "Mock", state: .connected))
+    return NavigationStack {
+        EEGDeviceDetails(device: model.activeDevice!) // swiftlint:disable:this force_unwrapping
+    }
+}
 
-    @StateObject static var modelIntervention = EEGViewModel(mock: MockEEGDevice(
+#Preview {
+    let modelIntervention = EEGViewModel(mock: MockEEGDevice(
         name: "Mock Device",
         model: "Mock",
         state: .interventionRequired("INTERVENTION_MUSE_FIRMWARE")
     ))
-
-    static var previews: some View {
-        if let device = model.activeDevice {
-            NavigationStack {
-                EEGDeviceDetails(device: device)
-            }
-        }
-
-        if let device = modelIntervention.activeDevice {
-            NavigationStack {
-                EEGDeviceDetails(device: device)
-            }
-        }
+    return NavigationStack {
+        EEGDeviceDetails(device: modelIntervention.activeDevice!) // swiftlint:disable:this force_unwrapping
     }
 }
 #endif

NAMS/EEG/EEGDeviceList.swift

@@ -10,7 +10,7 @@ import SwiftUI
 
 
 struct EEGDeviceList: View {
-    @ObservedObject private var eegModel: EEGViewModel
+    private let eegModel: EEGViewModel
 
     var sortedDeviceList: [EEGDevice] {
         eegModel.nearbyDevices.sorted { lhs, rhs in
@@ -32,13 +32,10 @@ struct EEGDeviceList: View {
 
 
 #if DEBUG
-struct MuseDeviceList_Previews: PreviewProvider {
-    @StateObject static var model = EEGViewModel(deviceManager: MockDeviceManager(immediate: true))
-
-    static var previews: some View {
-        List {
-            EEGDeviceList(eegModel: model)
-        }
+#Preview {
+    let model = EEGViewModel(deviceManager: MockDeviceManager(immediate: true))
+    return List {
+        EEGDeviceList(eegModel: model)
     }
 }
 #endif

NAMS/EEG/EEGDeviceRow.swift

@@ -11,8 +11,7 @@ import SwiftUI
 
 struct EEGDeviceRow: View {
     private let device: EEGDevice
-
-    @ObservedObject private var eegModel: EEGViewModel
+    private let eegModel: EEGViewModel
 
     var connectedDevice: ConnectedDevice? {
         if let activeDevice = eegModel.activeDevice,
@@ -34,7 +33,9 @@ struct EEGDeviceRow: View {
                 EEGDeviceDetails(device: item)
             }
             .accessibilityRepresentation {
-                let button = Button(action: deviceButtonAction) {
+                let button = Button(action: {
+                    deviceButtonAction()
+                }) {
                     Text(verbatim: device.model) // currently, this order flows best for Muse device naming
                     Text(verbatim: device.name)
                     if device.connectionState.associatedConnection {
@@ -61,8 +62,11 @@ struct EEGDeviceRow: View {
             }
     }
 
-    @ViewBuilder private var deviceButton: some View {
-        Button(action: deviceButtonAction) {
+
+    @MainActor @ViewBuilder private var deviceButton: some View {
+        Button(action: {
+            deviceButtonAction()
+        }) {
             HStack {
                 Text(verbatim: "\(device.model) - \(device.name)")
                     .foregroundColor(.primary)
@@ -106,6 +110,7 @@ struct EEGDeviceRow: View {
     }
 
 
+    @MainActor
     private func deviceButtonAction() {
         eegModel.tapDevice(device)
     }
@@ -117,42 +122,39 @@ struct EEGDeviceRow: View {
 
 
 #if DEBUG
-struct EEGDeviceRow_Previews: PreviewProvider {
-    struct StateRow: View {
-        static let device = MockEEGDevice(name: "Device", model: "Mock")
-        @StateObject var model = EEGViewModel(deviceManager: MockDeviceManager())
-        var body: some View {
-            EEGDeviceRow(eegModel: model, device: Self.device)
+#Preview {
+    let device = MockEEGDevice(name: "Device", model: "Mock")
+    let model = EEGViewModel(deviceManager: MockDeviceManager())
+
+    return NavigationStack {
+        List {
+            EEGDeviceRow(eegModel: model, device: device) // tap to pair
         }
     }
+}
 
-    static let devices = [
+#Preview {
+    NavigationStack {
+        List {
+            EEGDeviceRow(
+                eegModel: EEGViewModel(deviceManager: MockDeviceManager()),
+                device: MockEEGDevice(name: "Nearby Device", model: "Mock")
+            )
+        }
+    }
+}
+
+#Preview {
+    let devices = [
         MockEEGDevice(name: "Device 1", model: "Mock", state: .connecting),
         MockEEGDevice(name: "Device 2", model: "Mock", state: .connected),
         MockEEGDevice(name: "Device 3", model: "Mock", state: .interventionRequired("Firmware update required."))
     ]
 
-    static var previews: some View {
+    return ForEach(devices, id: \.macAddress) { device in
         NavigationStack {
             List {
-                StateRow() // tap to pair
-            }
-        }
-
-        NavigationStack {
-            List {
-                EEGDeviceRow(
-                    eegModel: EEGViewModel(deviceManager: MockDeviceManager()),
-                    device: MockEEGDevice(name: "Nearby Device", model: "Mock")
-                )
-            }
-        }
-
-        ForEach(devices, id: \.macAddress) { device in
-            NavigationStack {
-                List {
-                    EEGDeviceRow(eegModel: EEGViewModel(mock: device), device: device)
-                }
+                EEGDeviceRow(eegModel: EEGViewModel(mock: device), device: device)
             }
         }
     }

NAMS/EEG/EEGRecording.swift

@@ -15,7 +15,7 @@ struct EEGRecording: View {
     @Environment(\.dismiss)
     private var dismiss
 
-    @ObservedObject private var eegModel: EEGViewModel
+    private let eegModel: EEGViewModel
     @Environment(PatientListModel.self)
     private var patientList
 
@@ -110,8 +110,8 @@ struct EEGRecording: View {
 struct EEGMeasurement_Previews: PreviewProvider {
     static let connectedDevice = MockEEGDevice(name: "Device 1", model: "Mock", state: .connected)
 
-    @StateObject static var connectedModel = EEGViewModel(mock: connectedDevice)
-    @StateObject static var model = EEGViewModel(deviceManager: MockDeviceManager())
+    static let connectedModel = EEGViewModel(mock: connectedDevice)
+    static let model = EEGViewModel(deviceManager: MockDeviceManager())
 
     static var previews: some View {
         NavigationStack {

NAMS/EEG/ListRow.swift

@@ -31,8 +31,8 @@ struct ListRow<Value: View>: View {
 
 
 #if DEBUG
-struct ListRow_Previews: PreviewProvider {
-    static var previews: some View {
+#Preview {
+    List {
         ListRow("Hello") {
             Text(verbatim: "World")
         }

NAMS/EEG/Model/ConnectedDevice.swift

@@ -10,28 +10,41 @@ import Foundation
 import OrderedCollections
 
 
-class ConnectedDevice: ObservableObject {
+@Observable
+class ConnectedDevice {
     let device: EEGDevice
     var listener: DeviceConnectionListener?
 
-    @Published var state: ConnectionState = .unknown
+    var state: ConnectionState {
+        get {
+            access(keyPath: \.state)
+            return publishedState
+        }
+        set {
+            withMutation(keyPath: \.state) {
+                publishedState = newValue
+            }
+        }
+    }
+
+    @ObservationIgnored @Published var publishedState: ConnectionState = .unknown // current workaround to create a publisher for the view model
 
     // artifacts muse supports
-    @Published var wearingHeadband = false
-    @Published var eyeBlink = false
-    @Published var jawClench = false
+    var wearingHeadband = false
+    var eyeBlink = false
+    var jawClench = false
 
     /// Determines if the last second of data is considered good
-    @Published var isGood: (Bool, Bool, Bool, Bool) = (false, false, false, false) // swiftlint:disable:this large_tuple
+    var isGood: (Bool, Bool, Bool, Bool) = (false, false, false, false) // swiftlint:disable:this large_tuple
     /// The current fit of the headband
-    @Published var fit = HeadbandFit(tp9Fit: .poor, af7Fit: .poor, af8Fit: .poor, tp10Fit: .poor)
+    var fit = HeadbandFit(tp9Fit: .poor, af7Fit: .poor, af8Fit: .poor, tp10Fit: .poor)
 
-    @Published var aboutInformation: OrderedDictionary<LocalizedStringResource, CustomStringConvertible> = [:]
+    var aboutInformation: OrderedDictionary<LocalizedStringResource, CustomStringConvertible> = [:]
 
     /// Remaining battery percentage in percent [0.0;100.0]
-    @Published var remainingBatteryPercentage: Double?
+    var remainingBatteryPercentage: Double?
 
-    @Published var measurements: [EEGFrequency: [EEGSeries]] = [:]
+    var measurements: [EEGFrequency: [EEGSeries]] = [:]
 
     init(device: EEGDevice) {
         self.device = device

NAMS/EEG/Model/EEGViewModel.swift

@@ -11,13 +11,14 @@ import Foundation
 import OSLog
 
 
-class EEGViewModel: ObservableObject {
+@Observable
+class EEGViewModel {
     let logger = Logger(subsystem: "edu.stanford.NAMS", category: "MuseViewModel")
 
     private let deviceManager: DeviceManager
 
-    @Published var nearbyDevices: [EEGDevice] = []
-    @Published var activeDevice: ConnectedDevice?
+    var nearbyDevices: [EEGDevice] = []
+    var activeDevice: ConnectedDevice?
 
     private var deviceManagerCancelable: AnyCancellable?
     private var activeDeviceCancelable: AnyCancellable?
@@ -67,9 +68,7 @@ class EEGViewModel: ObservableObject {
             logger.info("Disconnecting previously connected device \(activeDevice.device.name)...")
             // either we tapped on the same Muse or on another one, in any case disconnect the currently active Muse
             activeDevice.disconnect()
-            activeDeviceCancelable?.cancel()
-            activeDeviceCancelable = nil
-            self.activeDevice = nil
+            clearActiveDevice()
 
 
             if activeDevice.device.macAddress == device.macAddress {
@@ -88,13 +87,16 @@ class EEGViewModel: ObservableObject {
     }
 
     func sinkActiveDevice(device: ConnectedDevice) {
-        activeDeviceCancelable = device.objectWillChange.sink { [weak self] in
-            self?.objectWillChange.send()
-            if case .disconnected = device.state {
-                self?.activeDeviceCancelable?.cancel()
-                self?.activeDeviceCancelable = nil
-                self?.activeDevice = nil
+        activeDeviceCancelable = device.$publishedState.sink { [weak self] state in
+            if case .disconnected = state {
+                self?.clearActiveDevice()
             }
         }
     }
+
+    private func clearActiveDevice() {
+        activeDeviceCancelable?.cancel()
+        activeDeviceCancelable = nil
+        activeDevice = nil
+    }
 }