编译UnityARKitPlugin遇到的问题

下载了UnityARKitPlugin，编译的时候在Xcode中链接的时候报错：

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Undefined symbols for architecture arm64:

  "_OBJC_CLASS_$_ARObjectScanningConfiguration", referenced from:

      objc-class-ref in ARKitNativeObjectDetection.o

  "_OBJC_CLASS_$_ARObjectAnchor", referenced from:

      objc-class-ref in ARKitNativeObjectDetection.o

  "_OBJC_CLASS_$_AREnvironmentProbeAnchor", referenced from:

      objc-class-ref in ARSessionNative.o

      objc-class-ref in AREnvironmentProbe.o

  "_OBJC_CLASS_$_ARWorldTrackingConfiguration", referenced from:

      objc-class-ref in ARSessionNative.o

  "_OBJC_CLASS_$_ARReferenceImage", referenced from:

      objc-class-ref in ARSessionNative.o

  "_OBJC_CLASS_$_AROrientationTrackingConfiguration", referenced from:

      objc-class-ref in ARSessionNative.o

  "_OBJC_CLASS_$_ARImageAnchor", referenced from:

      objc-class-ref in ARSessionNative.o

  "_OBJC_CLASS_$_ARAnchor", referenced from:

      objc-class-ref in ARSessionNative.o

  "_OBJC_CLASS_$_ARWorldMap", referenced from:

      objc-class-ref in ARWorldMap.o

      objc-class-ref in ARSessionNative.o

      objc-class-ref in ARKitNativeObjectDetection.o

  "_OBJC_CLASS_$_ARPlaneAnchor", referenced from:

      objc-class-ref in ARSessionNative.o

  "_OBJC_CLASS_$_ARSession", referenced from:

      objc-class-ref in ARSessionNative.o

  "_OBJC_CLASS_$_ARReferenceObject", referenced from:

      objc-class-ref in ARWorldMap.o

      objc-class-ref in ARSessionNative.o

      objc-class-ref in AREnvironmentProbe.o

      objc-class-ref in ARKitNativeObjectDetection.o

ld: symbol(s) not found for architecture arm64

clang: error: linker command failed with exit code 1 (use -v to see invocation)

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我使用的Unity版本是2019.4。解决的方案是在Unity的菜单 window -> Package Manager里面添加了ARKit XR Plugin。