fix: suspend OTG live transfer on exit

suixinkan/Features/TravelAlbum/OTG/Core/ConnectionManager.swift

@@ -36,6 +36,7 @@ protocol WiredCameraConnectionManaging: AnyObject {
     func configureLiveTransfer(albumID: Int?)
     func start()
     func unbindDelegate()
+    func suspendLiveTransfer()
     func disconnect()
 }
 
@@ -86,6 +87,11 @@ final class ConnectionManager: NSObject, WiredCameraConnectionManaging {
     func configureLiveTransfer(albumID: Int?) {
         liveTransferAlbumID = albumID
         OTGLog.debug(.connection, "live transfer album=\(albumID.map(String.init) ?? "nil")")
+        if albumID == nil {
+            stopLiveTransferServices()
+            return
+        }
+        resumeLiveTransferIfPossible()
     }
 
     /// Entry point when OTG UI appears: reconnect cached device or start discovery.
@@ -115,6 +121,13 @@ final class ConnectionManager: NSObject, WiredCameraConnectionManaging {
         cancelSearchTimers()
     }
 
+    /// 页面离开时暂停边拍边传轮询，保留 USB Session 与设备缓存。
+    func suspendLiveTransfer() {
+        OTGLog.info(.connection, "suspend live transfer")
+        liveTransferAlbumID = nil
+        stopLiveTransferServices()
+    }
+
     /// 断开 Session 并释放 Driver；缓存设备保留至 USB 拔出。
     func disconnect() {
         guard let device = activeDevice else {
@@ -131,12 +144,7 @@ final class ConnectionManager: NSObject, WiredCameraConnectionManaging {
         isClosingSession = true
         isContentCatalogReady = false
         cancelSearchTimers()
-        sonyRemoteCapture?.stop()
-        sonyRemoteCapture = nil
-        canonRemoteCapture?.stop()
-        canonRemoteCapture = nil
-        nikonLiveCapture?.stop()
-        nikonLiveCapture = nil
+        stopLiveTransferServices()
         liveTransferAlbumID = nil
         currentDriver?.disconnect()
         currentDriver = nil
@@ -305,12 +313,7 @@ final class ConnectionManager: NSObject, WiredCameraConnectionManaging {
     }
 
     private func clearDeviceCache() {
-        sonyRemoteCapture?.stop()
-        sonyRemoteCapture = nil
-        canonRemoteCapture?.stop()
-        canonRemoteCapture = nil
-        nikonLiveCapture?.stop()
-        nikonLiveCapture = nil
+        stopLiveTransferServices()
         cachedDevice = nil
         currentDriver?.disconnect()
         currentDriver = nil
@@ -428,24 +431,7 @@ private extension ConnectionManager {
                 await runGetDeviceInfoProbe(on: camera)
 
             case .sony:
-                let transactionID: UInt32 = 1
-                let result = await SonyPTPHelper.initializeRemoteSession(
-                    on: camera,
-                    startingTransactionID: transactionID
-                )
-                if result.success {
-                    let service = SonyRemoteCaptureService()
-                    service.onShotSaved = makeLiveShotSavedHandler()
-                    sonyRemoteCapture = service
-                    service.start(
-                        camera: camera,
-                        startingTransactionID: result.nextTransactionID,
-                        albumID: liveTransferAlbumID
-                    )
-                    OTGLog.info(.sony, "Sony remote session ready")
-                } else {
-                    OTGLog.error(.sony, "Sony remote session setup failed")
-                }
+                await startSonyLiveTransferIfNeeded(for: camera)
 
             default:
                 await runGetDeviceInfoProbe(on: camera)
@@ -474,10 +460,12 @@ private extension ConnectionManager {
     /// catalog 就绪后再初始化 Canon 远程模式，避免 SetRemoteMode 打断 SD 卡枚举。
     private func startCanonLiveTransferIfNeeded(for camera: ICCameraDevice) {
         guard canonRemoteCapture == nil else { return }
+        guard liveTransferAlbumID != nil else { return }
         guard PlatformDetector.detect(from: buildDeviceInfo(from: camera)) == .canon else { return }
 
         Task { @MainActor in
             try? await Task.sleep(nanoseconds: 500_000_000)
+            guard self.canonRemoteCapture == nil, self.liveTransferAlbumID != nil else { return }
 
             let transactionID: UInt32 = 1
             let result = await CanonPTPHelper.initializeRemoteSession(
@@ -504,6 +492,7 @@ private extension ConnectionManager {
     /// catalog 就绪后启动尼康边拍边传（didAdd + catalog 轮询，无需 PTP 远程会话）。
     private func startNikonLiveTransferIfNeeded(for camera: ICCameraDevice) {
         guard nikonLiveCapture == nil else { return }
+        guard liveTransferAlbumID != nil else { return }
         guard PlatformDetector.detect(from: buildDeviceInfo(from: camera)) == .nikon else { return }
 
         let service = NikonCatalogLiveCaptureService()
@@ -513,6 +502,57 @@ private extension ConnectionManager {
         OTGLog.info(.nikon, "Nikon catalog live capture ready")
     }
 
+    private func startSonyLiveTransferIfNeeded(for camera: ICCameraDevice) async {
+        guard sonyRemoteCapture == nil else { return }
+        guard liveTransferAlbumID != nil else { return }
+        guard PlatformDetector.detect(from: buildDeviceInfo(from: camera)) == .sony else { return }
+
+        let transactionID: UInt32 = 1
+        let result = await SonyPTPHelper.initializeRemoteSession(
+            on: camera,
+            startingTransactionID: transactionID
+        )
+        guard liveTransferAlbumID != nil else { return }
+        if result.success {
+            let service = SonyRemoteCaptureService()
+            service.onShotSaved = makeLiveShotSavedHandler()
+            sonyRemoteCapture = service
+            service.start(
+                camera: camera,
+                startingTransactionID: result.nextTransactionID,
+                albumID: liveTransferAlbumID
+            )
+            OTGLog.info(.sony, "Sony remote session ready")
+        } else {
+            OTGLog.error(.sony, "Sony remote session setup failed")
+        }
+    }
+
+    private func resumeLiveTransferIfPossible() {
+        guard let camera = cachedDevice, case .connected = state else { return }
+        switch PlatformDetector.detect(from: buildDeviceInfo(from: camera)) {
+        case .sony:
+            Task { await startSonyLiveTransferIfNeeded(for: camera) }
+        case .canon:
+            guard isContentCatalogReady else { return }
+            startCanonLiveTransferIfNeeded(for: camera)
+        case .nikon:
+            guard isContentCatalogReady else { return }
+            startNikonLiveTransferIfNeeded(for: camera)
+        case .unknown:
+            break
+        }
+    }
+
+    private func stopLiveTransferServices() {
+        sonyRemoteCapture?.stop()
+        sonyRemoteCapture = nil
+        canonRemoteCapture?.stop()
+        canonRemoteCapture = nil
+        nikonLiveCapture?.stop()
+        nikonLiveCapture = nil
+    }
+
     private func makeLiveShotSavedHandler() -> (String) -> Void {
         { [weak self] filename in
             guard let self, let albumID = self.liveTransferAlbumID else { return }
@@ -557,12 +597,7 @@ extension ConnectionManager: ICCameraDeviceDelegate {
         }
 
         isClosingSession = false
-        sonyRemoteCapture?.stop()
-        sonyRemoteCapture = nil
-        canonRemoteCapture?.stop()
-        canonRemoteCapture = nil
-        nikonLiveCapture?.stop()
-        nikonLiveCapture = nil
+        stopLiveTransferServices()
         currentDriver = nil
         isContentCatalogReady = false
         if let camera = device as? ICCameraDevice {