Synchronous VideoView internal state (#348)

Update VideoView's internal state synchronously so properties such as
avSampleBufferDisplayLayer can be accessed immediately.

Sources/LiveKit/Views/VideoView.swift

@@ -212,6 +212,8 @@ public class VideoView: NativeView, Loggable {
 
             guard let self else { return }
 
+            self.log("Mutating in main thread: \(Thread.current.isMainThread)", .trace)
+
             let shouldRenderDidUpdate = newState.shouldRender != oldState.shouldRender
             let renderModeDidUpdate = newState.renderMode != oldState.renderMode
 
@@ -220,8 +222,8 @@ public class VideoView: NativeView, Loggable {
 
             // Enter .main only if the following conditions are met...
             if trackDidUpdate || shouldRenderDidUpdate || renderModeDidUpdate {
-                Task.detached { @MainActor in
-
+                // Execute on main thread
+                self.mainSyncOrAsync {
                     var didReCreateNativeRenderer = false
 
                     if trackDidUpdate || shouldRenderDidUpdate {
@@ -244,7 +246,7 @@ public class VideoView: NativeView, Loggable {
                         // set new track
                         if let track = newState.track as? VideoTrack, newState.shouldRender {
                             // re-create renderer on main thread
-                            let nr = self.reCreateNativeRenderer()
+                            let nr = self.reCreateNativeRenderer(for: newState.renderMode)
                             didReCreateNativeRenderer = true
 
                             track.add(videoRenderer: self)
@@ -263,7 +265,7 @@ public class VideoView: NativeView, Loggable {
                     }
 
                     if renderModeDidUpdate, !didReCreateNativeRenderer {
-                        self.reCreateNativeRenderer()
+                        self.reCreateNativeRenderer(for: newState.renderMode)
                     }
                 }
             }
@@ -458,13 +460,13 @@ private extension VideoView {
     }
 
     @discardableResult
-    func reCreateNativeRenderer() -> NativeRendererView {
+    func reCreateNativeRenderer(for renderMode: VideoView.RenderMode) -> NativeRendererView {
         if !Thread.current.isMainThread {
             log("Must be called on main thread", .error)
         }
 
         // create a new rendererView
-        let newView = VideoView.createNativeRendererView(for: _state.renderMode)
+        let newView = VideoView.createNativeRendererView(for: renderMode)
         addSubview(newView)
 
         // keep the old rendererView
@@ -692,3 +694,15 @@ extension LKRTCMTLVideoView: Mirrorable {
         }
     }
 }
+
+private extension VideoView {
+    func mainSyncOrAsync(operation: @escaping () -> Void) {
+        if Thread.current.isMainThread {
+            operation()
+        } else {
+            Task.detached { @MainActor in
+                operation()
+            }
+        }
+    }
+}

Tests/LiveKitTests/VideoView.swift

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2024 LiveKit
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@testable import LiveKit
+import XCTest
+
+class VideoViewTests: XCTestCase {
+    override class func setUp() {
+        LiveKitSDK.setLoggerStandardOutput()
+    }
+
+    /// Test if avSampleBufferDisplayLayer is available immediately after creating VideoView.
+    @MainActor
+    func testAVSampleBufferDisplayLayer() {
+        let track = LocalVideoTrack.createCameraTrack()
+        let view = VideoView()
+        view.renderMode = .sampleBuffer
+        view.track = track
+        // avSampleBufferDisplayLayer should not be nil at this point
+        XCTAssert(view.avSampleBufferDisplayLayer != nil)
+    }
+}