fix pip screen bugs

shared/src/iosMain/kotlin/com/zhushenwudi/lovelivemusicplayer/player/PlayerController.ios.kt

@@ -14,7 +14,6 @@ import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import platform.AVFAudio.AVAudioSession
-import platform.AVFAudio.AVAudioSessionCategoryPlayback
 import platform.AVFAudio.AVAudioSessionInterruptionNotification
 import platform.AVFAudio.AVAudioSessionInterruptionOptionKey
 import platform.AVFAudio.AVAudioSessionInterruptionOptionShouldResume
@@ -24,7 +23,6 @@ import platform.AVFAudio.AVAudioSessionInterruptionTypeKey
 import platform.AVFAudio.AVAudioSessionRouteChangeNotification
 import platform.AVFAudio.AVAudioSessionRouteChangeReasonKey
 import platform.AVFAudio.AVAudioSessionRouteChangeReasonOldDeviceUnavailable
-import platform.AVFAudio.setActive
 import platform.AVFoundation.AVPlayer
 import platform.AVFoundation.AVPlayerItem
 import platform.AVFoundation.AVPlayerItemDidPlayToEndTimeNotification
@@ -131,6 +129,9 @@ actual class PlayerController {
     private var lastEndMark: TimeSource.Monotonic.ValueTimeMark? = null
 
     private var audioReady = false
+    private var audioActive = false
+    private var playWhenReady = false
+    private var audioSessionReadyObserver: Any? = null
 
     /** CarPlay / 锁屏 Now Playing 标题用的当前歌词；null 表示显示歌名。 */
     private var nowPlayingLyric: String? = null
@@ -143,18 +144,50 @@ actual class PlayerController {
         observePlaybackFailed()
         observeAudioRouteChanges()
         observeAudioInterruptions()
+        observeAudioSessionReady()
     }
 
     private fun ensureAudioReady() {
-        if (audioReady) return
+        if (audioActive || audioReady) return
         audioReady = true
-        runCatching {
-            val session = AVAudioSession.sharedInstance()
-            session.setCategory(AVAudioSessionCategoryPlayback, error = null)
-            session.setActive(true, error = null)
-        }.onFailure { AppLog.e(TAG, "ensureAudioReady session fail", it) }
         runCatching { setupRemoteCommands() }
             .onFailure { AppLog.e(TAG, "ensureAudioReady remoteCommands fail", it) }
+        NSNotificationCenter.defaultCenter.postNotificationName(
+            aName = "llmpPrepareAudioSession",
+            `object` = null,
+            userInfo = null,
+        )
+    }
+
+    private fun observeAudioSessionReady() {
+        audioSessionReadyObserver = NSNotificationCenter.defaultCenter.addObserverForName(
+            name = "llmpAudioSessionReady",
+            `object` = null,
+            queue = null,
+        ) { notification: NSNotification? ->
+            val ok = (notification?.userInfo?.get("ok") as? NSNumber)?.boolValue ?: true
+            dispatch_async(dispatch_get_main_queue()) {
+                if (!ok) {
+                    audioReady = false
+                    playWhenReady = false
+                    AppLog.e(TAG, "audio session activate failed")
+                    if (_state.value.isPlaying) {
+                        player.pause()
+                        _state.update { it.copy(isPlaying = false) }
+                    }
+                    return@dispatch_async
+                }
+                audioActive = true
+                if (playWhenReady && _state.value.isPlaying) {
+                    playWhenReady = false
+                    player.play()
+                    startPositionUpdates()
+                    updateNowPlayingInfo()
+                } else {
+                    playWhenReady = false
+                }
+            }
+        }
     }
 
     private fun setupRemoteCommands() {
@@ -270,7 +303,7 @@ actual class PlayerController {
             queue = null,
         ) { notification: NSNotification? ->
             val ended = notification?.`object` as? AVPlayerItem
-            // 桌面歌词 dummy black.mp4 也会发 DidPlayToEnd；只处理本控制器的音乐 item。
+            // 只处理本控制器的音乐 item。
             // Kotlin/Native 的 === 对 ObjC 对象包装器不可靠，须用 isEqual 比较指针。
             if (ended == null || !isMusicItem(ended)) {
                 return@addObserverForName
@@ -614,17 +647,24 @@ actual class PlayerController {
         ensureAudioReady()
         val current = _state.value.current
         if (loadedUri.isNullOrBlank() && current != null) {
+            playWhenReady = false
             AppLog.e(TAG, "play() abort reason=noLoadedUri id=${current.musicId}")
             _state.update { it.copy(isPlaying = false, error = "No playable URI") }
             return
         }
-        player.play()
         _state.update { it.copy(isPlaying = true, error = null) }
-        startPositionUpdates()
-        updateNowPlayingInfo()
+        if (audioActive) {
+            player.play()
+            startPositionUpdates()
+            updateNowPlayingInfo()
+        } else {
+            playWhenReady = true
+            updateNowPlayingInfo()
+        }
     }
 
     actual fun pause() {
+        playWhenReady = false
         resumeAfterInterruption = false
         endScrub()
         player.pause()
@@ -908,8 +948,12 @@ actual class PlayerController {
         watchItemStatus(item, path, music)
         if (autoPlay) {
             ensureAudioReady()
-            player.play()
-            startPositionUpdates()
+            if (audioActive) {
+                player.play()
+                startPositionUpdates()
+            } else {
+                playWhenReady = true
+            }
         } else {
             player.pause()
             positionJob?.cancel()