ほかのmain thread使ってるところ修正とコメント追加

Sources/Kitsunebi/AnimationView.swift

@@ -18,6 +18,7 @@ open class PlayerView: UIView {
   override open class var layerClass: Swift.AnyClass {
     return CAMetalLayer.self
   }
+  // self.layer main thread使う必要あるので、事前に持つことでmain thread以外のthreadでも使えるように
   private lazy var gpuLayer: LayerClass = { fatalError("gpuLayer must be init") }()
   private let renderQueue: DispatchQueue = .global(qos: .userInitiated)
   private let commandQueue: MTLCommandQueue
@@ -126,12 +127,9 @@ open class PlayerView: UIView {
   }
 
   private func clear() {
-    DispatchQueue.main.async { [weak self] in
-      /// `gpuLayer` must access within main-thread.
+    renderQueue.async { [weak self] in
       guard let nextDrawable = self?.gpuLayer.nextDrawable() else { return }
-      self?.renderQueue.async { [weak self] in
-        self?.clear(nextDrawable: nextDrawable)
-      }
+      self?.clear(nextDrawable: nextDrawable)
     }
   }
 
@@ -196,13 +194,14 @@ open class PlayerView: UIView {
 extension PlayerView: VideoEngineUpdateDelegate {
   internal func didOutputFrame(_ frame: Frame) {
     guard applicationHandler.isActive else { return }
-    guard let nextDrawable = gpuLayer.nextDrawable() else { return }
-    gpuLayer.drawableSize = frame.size
+
     renderQueue.async { [weak self] in
+      guard let self = self, let nextDrawable = self.gpuLayer.nextDrawable() else { return }
+      self.gpuLayer.drawableSize = frame.size
       do {
-        try self?.renderImage(with: frame, to: nextDrawable)
+        try self.renderImage(with: frame, to: nextDrawable)
       } catch {
-        self?.clear(nextDrawable: nextDrawable)
+        self.clear(nextDrawable: nextDrawable)
       }
     }
   }