fix a bug about ios

ios/OralTrainer/Player/PlayerSurfaceView.swift

@@ -5,24 +5,29 @@ import UIKit
 /// 与安卓端 OralTrainerPlayerView 对齐的播放区：
 /// - 单击：播放 / 暂停
 /// - 左划 / 右划：上一句 / 下一句（无句边界时回退为快退 / 快进）
+/// - 上划 / 下划：显示 / 隐藏字幕层（由 SwiftUI 横屏页接收）
 /// - 长按：按触摸点水平位置变速（左慢右快），松手恢复原速
 struct PlayerSurfaceView: UIViewRepresentable {
     let controller: PlayerController
+    var onVerticalSwipe: ((Bool) -> Void)?
 
     func makeUIView(context: Context) -> VideoSurfaceView {
         let view = VideoSurfaceView()
         view.playerLayer.player = controller.player
         view.controller = controller
+        view.onVerticalSwipe = onVerticalSwipe
         return view
     }
 
     func updateUIView(_ uiView: VideoSurfaceView, context: Context) {
         uiView.playerLayer.player = controller.player
+        uiView.onVerticalSwipe = onVerticalSwipe
     }
 }
 
 final class VideoSurfaceView: UIView {
     weak var controller: PlayerController?
+    var onVerticalSwipe: ((Bool) -> Void)?
 
     override class var layerClass: AnyClass {
         AVPlayerLayer.self
@@ -82,6 +87,12 @@ final class VideoSurfaceView: UIView {
         let velocity = recognizer.velocity(in: self)
         let dx = translation.x
         let dy = translation.y
+        if abs(dy) > abs(dx),
+           abs(dy) >= minSwipeDistance,
+           abs(velocity.y) >= minSwipeVelocity {
+            onVerticalSwipe?(dy < 0)
+            return
+        }
         guard abs(dx) >= abs(dy),
               abs(dx) >= minSwipeDistance,
               abs(velocity.x) >= minSwipeVelocity else {