From cc382fd57138c215845fbb0b6cb5be89e50afada Mon Sep 17 00:00:00 2001
From: Ben Doherty <bendoherty@google.com>
Date: Mon, 18 Aug 2025 15:18:53 -0400
Subject: [PATCH] Metal: verify that the native window is a CAMetalLayer
 (#9104)

---
 filament/backend/CMakeLists.txt            | 1 +
 filament/backend/src/metal/MetalHandles.mm | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/filament/backend/CMakeLists.txt b/filament/backend/CMakeLists.txt
index a6d941d140..ec77a49c2c 100644
--- a/filament/backend/CMakeLists.txt
+++ b/filament/backend/CMakeLists.txt
@@ -412,6 +412,7 @@ endif()
 
 if (APPLE AND NOT IOS)
     target_link_libraries(${TARGET} PRIVATE "-framework Cocoa")
+    target_link_libraries(${TARGET} PRIVATE "-framework QuartzCore")
 endif()
 
 target_link_libraries(${TARGET} PUBLIC math)
diff --git a/filament/backend/src/metal/MetalHandles.mm b/filament/backend/src/metal/MetalHandles.mm
index f6d3190c06..317173544d 100644
--- a/filament/backend/src/metal/MetalHandles.mm
+++ b/filament/backend/src/metal/MetalHandles.mm
@@ -118,6 +118,10 @@ MetalSwapChain::MetalSwapChain(
       layerDrawableMutex(std::make_shared<std::mutex>()),
       type(SwapChainType::CAMETALLAYER) {
 
+    FILAMENT_CHECK_PRECONDITION([nativeWindow isKindOfClass:[CAMetalLayer class]])
+            << "nativeWindow pointer of class "
+            << [NSStringFromClass([nativeWindow class]) UTF8String] << " is not a CAMetalLayer";
+
     if (!(flags & SwapChain::CONFIG_TRANSPARENT) && !nativeWindow.opaque) {
         LOG(WARNING) << "Warning: Filament SwapChain has no CONFIG_TRANSPARENT flag, but the "
                         "CAMetaLayer("