Burn down SwiftLint advisory violations from 109 to 4 (#1362)

Mechanical style fixes across the enabled rule set, mostly via
swiftlint --fix (trailing_comma, comma, colon, trailing_newline,
comment_spacing, unused_closure_parameter, unneeded_break_in_switch,
opening_brace) plus hand fixes:

- non_optional_string_data_conversion (45): .data(using: .utf8)! and
  ?? Data() fallbacks replaced with the non-optional Data(_.utf8),
  including two production sites (NIP-44 HKDF info constant and the
  announce canonicalization context/nickname bytes — byte-identical
  output, only the impossible-nil handling is gone).
- switch_case_alignment: LocationChannel had a misindented closing
  brace; also repaired an --fix artifact in BLEService's .none case.
- redundant_string_enum_value: TrustLevel raw values equal to the case
  names (encoded form unchanged).
- unused_optional_binding: let _ = binds replaced with != nil / is Bool.
- static_over_final_class: PreviewView.layerClass.
- Resolved the BinaryProtocolTests TODO by documenting that 8-byte
  recipient ID truncation is the fixed wire-field size, not a bug.

The 4 remaining violations are all todo markers for a shared
test-helpers module (tracked in #1088) and one Reuse note.

Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

bitchat/BitchatApp.swift

@@ -71,7 +71,7 @@ struct BitchatApp: App {
 final class AppDelegate: NSObject, UIApplicationDelegate {
     weak var runtime: AppRuntime?
 
-    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
+    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil) -> Bool {
         true
     }
 

bitchat/Identity/IdentityModels.swift

@@ -127,10 +127,10 @@ struct SocialIdentity: Codable {
 }
 
 enum TrustLevel: String, Codable {
-    case unknown = "unknown"
-    case casual = "casual"
-    case trusted = "trusted"
-    case verified = "verified"
+    case unknown
+    case casual
+    case trusted
+    case verified
 }
 
 // MARK: - Identity Cache

bitchat/Nostr/NostrProtocol.swift

@@ -648,7 +648,7 @@ private extension NostrProtocol {
         let derivedKey = HKDF<CryptoKit.SHA256>.deriveKey(
             inputKeyMaterial: SymmetricKey(data: sharedSecretData),
             salt: Data(),
-            info: "nip44-v2".data(using: .utf8)!,
+            info: Data("nip44-v2".utf8),
             outputByteCount: 32
         )
         return derivedKey.withUnsafeBytes { Data($0) }

bitchat/Nostr/XChaCha20Poly1305Compat.swift

@@ -132,4 +132,3 @@ private extension Data {
         replaceSubrange(offset..<(offset+4), with: bytes)
     }
 }
-

bitchat/Protocols/LocationChannel.swift

@@ -18,7 +18,7 @@ enum GeohashChannelLevel: CaseIterable, Codable, Equatable {
         case .city: return 5
         case .province: return 4
         case .region: return 2
-    }
+        }
     }
 
     var displayName: String {

bitchat/Services/BLE/BLEService.swift

@@ -1305,7 +1305,7 @@ extension BLEService: GossipSyncManager.Delegate {
 
 extension BLEService: CBCentralManagerDelegate {
     #if os(iOS)
-    func centralManager(_ central: CBCentralManager, willRestoreState dict: [String : Any]) {
+    func centralManager(_ central: CBCentralManager, willRestoreState dict: [String: Any]) {
         let restoredPeripherals = (dict[CBCentralManagerRestoredStatePeripheralsKey] as? [CBPeripheral]) ?? []
         let restoredServices = (dict[CBCentralManagerRestoredStateScanServicesKey] as? [CBUUID]) ?? []
         let restoredOptions = (dict[CBCentralManagerRestoredStateScanOptionsKey] as? [String: Any]) ?? [:]
@@ -1987,7 +1987,7 @@ extension BLEService: CBPeripheralManagerDelegate {
     }
     
     #if os(iOS)
-    func peripheralManager(_ peripheral: CBPeripheralManager, willRestoreState dict: [String : Any]) {
+    func peripheralManager(_ peripheral: CBPeripheralManager, willRestoreState dict: [String: Any]) {
         let restoredServices = (dict[CBPeripheralManagerRestoredStateServicesKey] as? [CBMutableService]) ?? []
         let restoredAdvertisement = (dict[CBPeripheralManagerRestoredStateAdvertisementDataKey] as? [String: Any]) ?? [:]
 
@@ -2956,10 +2956,9 @@ extension BLEService {
             
         case .leave:
             handleLeave(packet, from: senderID)
-            
+
         case .none:
             SecureLogger.warning("⚠️ Unknown message type: \(packet.type)", category: .session)
-            break
         }
         
         if forwardAlongRouteIfNeeded(packet) {

bitchat/Services/MessageRouter.swift

@@ -51,7 +51,7 @@ final class MessageRouter {
             }
             // Handle key updates
             if let newKey = note.userInfo?["peerPublicKey"] as? Data,
-               let _ = note.userInfo?["isKeyUpdate"] as? Bool {
+               note.userInfo?["isKeyUpdate"] is Bool {
                 let peerID = PeerID(publicKey: newKey)
                 Task { @MainActor in
                     self.flushOutbox(for: peerID)

bitchat/Services/NoiseEncryptionService.swift

@@ -428,7 +428,7 @@ final class NoiseEncryptionService {
     private func canonicalAnnounceBytes(peerID: Data, noiseKey: Data, ed25519Key: Data, nickname: String, timestampMs: UInt64) -> Data {
         var out = Data()
         // context
-        let context = "bitchat-announce-v1".data(using: .utf8) ?? Data()
+        let context = Data("bitchat-announce-v1".utf8)
         out.append(UInt8(min(context.count, 255)))
         out.append(context.prefix(255))
         // peerID (expect 8 bytes; pad/truncate to 8 for canonicalization)
@@ -444,7 +444,7 @@ final class NoiseEncryptionService {
         out.append(ed32)
         if ed32.count < 32 { out.append(Data(repeating: 0, count: 32 - ed32.count)) }
         // nickname length + bytes
-        let nickData = nickname.data(using: .utf8) ?? Data()
+        let nickData = Data(nickname.utf8)
         out.append(UInt8(min(nickData.count, 255)))
         out.append(nickData.prefix(255))
         // timestamp

bitchat/Services/NostrTransport.swift

@@ -137,7 +137,7 @@ final class NostrTransport: Transport, @unchecked Sendable {
     }
     
     func peerNickname(peerID: PeerID) -> String? { nil }
-    func getPeerNicknames() -> [PeerID : String] { [:] }
+    func getPeerNicknames() -> [PeerID: String] { [:] }
 
     func getFingerprint(for peerID: PeerID) -> String? { nil }
     func getNoiseSessionState(for peerID: PeerID) -> LazyHandshakeState { .none }

bitchat/Services/NotificationService.swift

@@ -111,7 +111,7 @@ final class NotificationService {
 
     func requestAuthorization() {
         guard !isRunningTests else { return }
-        authorizer.requestAuthorization(options: [.alert, .sound, .badge]) { granted, error in
+        authorizer.requestAuthorization(options: [.alert, .sound, .badge]) { granted, _ in
             if granted {
                 // Permission granted
             } else {

bitchat/Utils/PeerDisplayNameResolver.swift

@@ -27,4 +27,3 @@ struct PeerDisplayNameResolver {
         return result
     }
 }
-

bitchat/ViewModels/ChatNostrCoordinator.swift

@@ -71,7 +71,7 @@ final class ChatNostrCoordinator {
         key: Data?
     ) {
         guard let context else { return }
-        if let _ = key {
+        if key != nil {
             if let identity = context.currentNostrIdentity() {
                 context.sendGeohashDeliveryAck(for: message.id, toRecipientHex: senderPubkey, from: identity)
             }
@@ -84,7 +84,7 @@ final class ChatNostrCoordinator {
         }
 
         if !wasReadBefore && context.selectedPrivateChatPeer == message.senderPeerID {
-            if let _ = key {
+            if key != nil {
                 if let identity = context.currentNostrIdentity() {
                     context.sendGeohashReadReceipt(message.id, toRecipientHex: senderPubkey, from: identity)
                 }

bitchat/Views/MessageListView.swift

@@ -426,6 +426,6 @@ private extension ChannelID {
     }
 }
 
-//#Preview {
+// #Preview {
 //    MessageListView()
-//}
+// }

bitchat/Views/VerificationViews.swift

@@ -265,7 +265,7 @@ struct CameraScannerView: UIViewRepresentable {
     }
 
     final class PreviewView: UIView {
-        override class var layerClass: AnyClass { AVCaptureVideoPreviewLayer.self }
+        override static var layerClass: AnyClass { AVCaptureVideoPreviewLayer.self }
         var videoPreviewLayer: AVCaptureVideoPreviewLayer { layer as! AVCaptureVideoPreviewLayer }
         override init(frame: CGRect) {
             super.init(frame: frame)