feat: add connected devices - cleanup some restoration bits

Author: dballance

packages/flutter_reactive_ble/lib/src/reactive_ble.dart

@@ -300,6 +300,13 @@ class FlutterReactiveBle {
             ),
           );
 
+  /// Gets a list of connection states for connected devices
+  /// Useful when restoring devices via iOS state restoration
+  Future<List<ConnectionStateUpdate>> getConnectedDevices() async {
+    await initialize();
+    return _blePlatform.getConnectedDevices();
+  }
+
   /// Disconnects a device with the provided id.
   ///
   /// Useful for restored devices where a connection subscription is not obtained.

packages/reactive_ble_mobile/ios/Classes/BleData/bledata.pb.swift

@@ -599,6 +599,18 @@ struct DiscoveredCharacteristic {
   fileprivate var _serviceID: Uuid? = nil
 }
 
+struct DeviceInfoCollection {
+  // SwiftProtobuf.Message conformance is added in an extension below. See the
+  // `Message` and `Message+*Additions` files in the SwiftProtobuf library for
+  // methods supported on all messages.
+
+  var devices: [DeviceInfo] = []
+
+  var unknownFields = SwiftProtobuf.UnknownStorage()
+
+  init() {}
+}
+
 struct Uuid {
   // SwiftProtobuf.Message conformance is added in an extension below. See the
   // `Message` and `Message+*Additions` files in the SwiftProtobuf library for
@@ -653,6 +665,7 @@ extension DiscoverServicesRequest: @unchecked Sendable {}
 extension DiscoverServicesInfo: @unchecked Sendable {}
 extension DiscoveredService: @unchecked Sendable {}
 extension DiscoveredCharacteristic: @unchecked Sendable {}
+extension DeviceInfoCollection: @unchecked Sendable {}
 extension Uuid: @unchecked Sendable {}
 extension GenericFailure: @unchecked Sendable {}
 #endif  // swift(>=5.5) && canImport(_Concurrency)
@@ -1801,6 +1814,38 @@ extension DiscoveredCharacteristic: SwiftProtobuf.Message, SwiftProtobuf._Messag
   }
 }
 
+extension DeviceInfoCollection: SwiftProtobuf.Message, SwiftProtobuf._MessageImplementationBase, SwiftProtobuf._ProtoNameProviding {
+  static let protoMessageName: String = "DeviceInfoCollection"
+  static let _protobuf_nameMap: SwiftProtobuf._NameMap = [
+    1: .same(proto: "devices"),
+  ]
+
+  mutating func decodeMessage<D: SwiftProtobuf.Decoder>(decoder: inout D) throws {
+    while let fieldNumber = try decoder.nextFieldNumber() {
+      // The use of inline closures is to circumvent an issue where the compiler
+      // allocates stack space for every case branch when no optimizations are
+      // enabled. https://github.com/apple/swift-protobuf/issues/1034
+      switch fieldNumber {
+      case 1: try { try decoder.decodeRepeatedMessageField(value: &self.devices) }()
+      default: break
+      }
+    }
+  }
+
+  func traverse<V: SwiftProtobuf.Visitor>(visitor: inout V) throws {
+    if !self.devices.isEmpty {
+      try visitor.visitRepeatedMessageField(value: self.devices, fieldNumber: 1)
+    }
+    try unknownFields.traverse(visitor: &visitor)
+  }
+
+  static func ==(lhs: DeviceInfoCollection, rhs: DeviceInfoCollection) -> Bool {
+    if lhs.devices != rhs.devices {return false}
+    if lhs.unknownFields != rhs.unknownFields {return false}
+    return true
+  }
+}
+
 extension Uuid: SwiftProtobuf.Message, SwiftProtobuf._MessageImplementationBase, SwiftProtobuf._ProtoNameProviding {
   static let protoMessageName: String = "Uuid"
   static let _protobuf_nameMap: SwiftProtobuf._NameMap = [

packages/reactive_ble_mobile/ios/Classes/Plugin/PluginController.swift

@@ -72,7 +72,7 @@ final class PluginController {
                 case .restored: 
                     message = DeviceInfo.with {
                         $0.id = peripheral.identifier.uuidString
-                        /// The value for a restored device.
+                        // Restored device state is different from peripheral state from connection manager
                         $0.connectionState = 4
                     }
 
@@ -260,6 +260,30 @@ final class PluginController {
         }
     }
 
+    func getConnectedDevices(name: String, completion: @escaping PlatformMethodCompletionHandler) {
+        guard let central = central
+        else {
+            completion(.failure(PluginError.notInitialized.asFlutterError))
+            return
+        }
+        
+        let devices = central.getConnectedDevices()
+
+        if let sink = connectedDeviceSink {
+            devices.forEach { device in 
+                sink.add(.success(device))
+            }
+        } else {
+            print("Warning! No event channel set up to report a connection update")
+        }
+        
+        let message = DeviceInfoCollection.with {
+            $0.devices = central.getConnectedDevices()
+        }
+
+        completion(.success(message))
+    }
+
     func disconnectFromDevice(name: String, args: ConnectToDeviceRequest, completion: @escaping PlatformMethodCompletionHandler) {
         guard let central = central
         else {

packages/reactive_ble_mobile/ios/Classes/Plugin/SwiftReactiveBlePlugin.swift

@@ -96,6 +96,9 @@ public class SwiftReactiveBlePlugin: NSObject, FlutterPlugin {
         AnyPlatformMethod(UnaryPlatformMethod(name: "connectToDevice") { (name, context, args: ConnectToDeviceRequest, completion) in
             context.connectToDevice(name: name, args: args, completion: completion)
         }),
+        AnyPlatformMethod(NullaryPlatformMethod(name: "getConnectedDevices") { name, context, completion in
+            context.getConnectedDevices(name: name, completion: completion)
+        }),
         AnyPlatformMethod(UnaryPlatformMethod(name: "disconnectFromDevice") { (name, context, args: ConnectToDeviceRequest, completion) in
             context.disconnectFromDevice(name: name, args: args, completion: completion)
         }),

packages/reactive_ble_mobile/ios/Classes/ReactiveBle/Central.swift

@@ -66,28 +66,36 @@ final class Central {
                 case .restored:
                     peripheral.delegate = self.peripheralDelegate
                     central.activePeripherals[peripheral.identifier] = peripheral
-                    
-                    if (central.hasMissingServicesOrCharacteristics(for: peripheral)) {
-                        NSLog("flutter: Has missing services, discovering")
-                        // We're missing services, so schedule an discovery task
-                        // on all services / characteristics
-                        DispatchQueue.main.asyncAfter(deadline: .now() + 0.300) {
-                            do {
-                                
-                                try central.discoverServicesWithCharacteristics(
-                                    for: peripheral.identifier,
-                                    discover: .all,
-                                    completion:central.onServicesWithCharacteristicsInitialDiscovery
-                                )
-                            } catch {
-                                return;
-                            }
+
+                    // If a restored device has services that are reporting characteristics
+                    // it's likely that we have all the services and characteristics previously
+                    // discovered for the device.
+                    //
+                    // However, if we have no services OR have services that have no characteristics
+                    // (according to Apple docs - if characteristics of a service are nil, they've not been discovered)
+                    // we must discover services on the device to properly subscribe to them upon restoration
+                    if (!central.hasMissingServicesOrCharacteristics(for: peripheral)) {
+                        break
+                    }
+
+                    onConnectionChange(central, peripheral, .connected)
+                    // We're missing services, so schedule an discovery task
+                    // on all services / characteristics
+                    DispatchQueue.main.asyncAfter(deadline: .now() + 0.300) {
+                        do {
+                            
+                            try central.discoverServicesWithCharacteristics(
+                                for: peripheral.identifier,
+                                discover: .all,
+                                completion:central.onServicesWithCharacteristicsInitialDiscovery
+                            )
+                        } catch {
+                            print("Error restoring services or characteristics for peripheral. ID: \(peripheral.identifier) Error: \(error)")
                         }
-                        
-                        return;
                     }
-                    
-                    break
+
+                    return
+
                 case .failedToConnect(let error), .disconnected(let error):
                     central.eject(peripheral, error: error ?? PluginError.connectionLost)
                 }
@@ -148,6 +156,15 @@ final class Central {
         isScanning = false
     }
 
+    func getConnectedDevices() -> [DeviceInfo] {
+        return activePeripherals.map { _, peripheral in
+            return DeviceInfo.with {
+                $0.id = peripheral.identifier.uuidString
+                $0.connectionState = encode(peripheral.state)
+            }
+        }
+    }
+
     func connect(to peripheralID: PeripheralID, discover servicesWithCharacteristicsToDiscover: ServicesWithCharacteristicsToDiscover, timeout: TimeInterval?) throws {
         let peripheral = try resolve(known: peripheralID)
 

packages/reactive_ble_mobile/lib/src/converter/protobuf_converter.dart

@@ -13,6 +13,8 @@ abstract class ProtobufConverter {
 
   ConnectionStateUpdate connectionStateUpdateFrom(List<int> data);
 
+  List<ConnectionStateUpdate> connectedDevicesFrom(List<int> data);
+
   Result<Unit, GenericFailure<ClearGattCacheError>?> clearGattCacheResultFrom(
     List<int> data,
   );
@@ -93,6 +95,28 @@ class ProtobufConverterImpl implements ProtobufConverter {
     );
   }
 
+  @override
+  List<ConnectionStateUpdate> connectedDevicesFrom(List<int> data) {
+    final collection = pb.DeviceInfoCollection.fromBuffer(data);
+
+    return collection.devices
+        .map((info) => ConnectionStateUpdate(
+              deviceId: info.id,
+              connectionState: selectFrom(
+                DeviceConnectionState.values,
+                index: info.connectionState,
+                fallback: (int? raw) => throw _InvalidConnectionState(raw),
+              ),
+              failure: genericFailureFrom(
+                hasFailure: info.hasFailure(),
+                getFailure: () => info.failure,
+                codes: ConnectionError.values,
+                fallback: (int? rawOrNull) => ConnectionError.unknown,
+              ),
+            ))
+        .toList();
+  }
+
   @override
   Result<Unit, GenericFailure<ClearGattCacheError>?> clearGattCacheResultFrom(
       List<int> data) {

packages/reactive_ble_mobile/lib/src/generated/bledata.pb.dart

@@ -148,6 +148,18 @@ class ReactiveBleMobilePlatform extends ReactiveBlePlatform {
         .asStream();
   }
 
+  @override
+  Future<List<ConnectionStateUpdate>> getConnectedDevices() {
+    _logger?.log(
+      'Get connected devices',
+    );
+    return _bleMethodChannel
+        .invokeMethod<List<int>>(
+          "getConnectedDevices",
+        )
+        .then((data) => _protobufConverter.connectedDevicesFrom(data!));
+  }
+
   @override
   Future<void> disconnectDevice(String deviceId) {
     _logger?.log(

packages/reactive_ble_mobile/lib/src/generated/bledata.pbjson.dart

@@ -145,6 +145,10 @@ message DiscoveredCharacteristic {
     bool isIndicatable = 7;
 }
 
+message DeviceInfoCollection {
+    repeated DeviceInfo devices = 1;
+}
+
 message Uuid {
     bytes data = 1;
 }