?

flake.nix

@@ -8,25 +8,31 @@
     system = "aarch64-darwin";
     pkgs = nixpkgs.legacyPackages.${system};
   in {
-    # This builds the 'PROCESSOR' library so other projects can find it
     packages.${system}.default = pkgs.stdenv.mkDerivation {
       name = "image_processor";
       src = ./.;
-      nativeBuildInputs = [pkgs.cmake];
+
+      # Add pkg-config here so CMake can find it during the build
+      nativeBuildInputs = [
+        pkgs.cmake
+        pkgs.pkg-config
+      ];
+
       buildInputs = [pkgs.libjpeg_turbo];
-      # This ensures the .dylib and .h files are moved to the right place
+
+      # Nix's default CMake phase will run, but we need to ensure
+      # the library actually gets installed to the nix store output
       installPhase = ''
         mkdir -p $out/lib $out/include
-        cp libPROCESSOR.dylib $out/lib/ || cp libPROCESSOR.a $out/lib/
+        cp libPROCESSOR.dylib $out/lib/ 2>/dev/null || cp libPROCESSOR.a $out/lib/
         cp *.h $out/include/
       '';
     };
 
     devShells.${system}.default = pkgs.mkShell {
+      # This makes sure the shell also has the tools for manual debugging
+      nativeBuildInputs = [pkgs.pkg-config pkgs.cmake];
       buildInputs = [pkgs.libjpeg_turbo];
-      shellHook = ''
-        export PKG_CONFIG_PATH="${pkgs.libjpeg_turbo.dev}/lib/pkgconfig:$PKG_CONFIG_PATH"
-      '';
     };
   };
 }