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OpenCV plus Unity の顔検出を iOS で行う

Unity iOS OpenCV

OpenCV plus Unity(無料) は PC(自分は Mac) 上ではインポートしてそのまま iOS 向けに Build すると Build 時にエラーが出たのでその対処方法

環境

Mac
Unity 2021.1.7f1
iPhone 12 Pro
OpenCV plus Unity 1.7.1

参考にしたリンク

エラー1

Exception: IL2CPP error (no further information about what managed code was being converted is available)
Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'
   at Unity.Cecil.Awesome.AssemblyResolver.ResolveInternal(AssemblyNameReference name) in /Users/bokken/build/output/unity/il2cpp/Unity.Cecil.Awesome/AssemblyResolver.cs:line 153
   at Unity.Cecil.Awesome.AssemblyResolver.Resolve(AssemblyNameReference name) in /Users/bokken/build/output/unity/il2cpp/Unity.Cecil.Awesome/AssemblyResolver.cs:line 62
   at Unity.Cecil.Awesome.WindowsRuntimeAwareMetadataResolver.Resolve(TypeReference type) in /Users/bokken/build/output/unity/il2cpp/Unity.Cecil.Awesome/WindowsRuntimeAwareMetadataResolver.cs:line 99

エラー全文

Exception: IL2CPP error (no further information about what managed code was being converted is available)
Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'
   at Unity.Cecil.Awesome.AssemblyResolver.ResolveInternal(AssemblyNameReference name) in /Users/bokken/build/output/unity/il2cpp/Unity.Cecil.Awesome/AssemblyResolver.cs:line 153
   at Unity.Cecil.Awesome.AssemblyResolver.Resolve(AssemblyNameReference name) in /Users/bokken/build/output/unity/il2cpp/Unity.Cecil.Awesome/AssemblyResolver.cs:line 62
   at Unity.Cecil.Awesome.WindowsRuntimeAwareMetadataResolver.Resolve(TypeReference type) in /Users/bokken/build/output/unity/il2cpp/Unity.Cecil.Awesome/WindowsRuntimeAwareMetadataResolver.cs:line 99
   at Mono.Cecil.Mixin.CheckedResolve(TypeReference self)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeEnum(TypeReference enum_type)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeElement(TypeReference type)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeNamedArgument(Collection`1& fields, Collection`1& properties)
   at Mono.Cecil.SignatureReader.ReadCustomAttributeNamedArguments(UInt16 count, Collection`1& fields, Collection`1& properties)
   at Mono.Cecil.SignatureReader.ReadSecurityAttribute()
   at Mono.Cecil.MetadataReader.ReadSecurityDeclarationSignature(SecurityDeclaration declaration)
   at Mono.Cecil.SecurityDeclaration.<Resolve>b__19_0(SecurityDeclaration declaration, MetadataReader reader)
   at Mono.Cecil.ModuleDefinition.Read[TItem,TRet](TItem item, Func`3 read)
   at Mono.Cecil.SecurityDeclaration.Resolve()
   at Mono.Cecil.SecurityDeclaration.get_SecurityAttributes()
   at Mono.Cecil.ImmediateModuleReader.ReadSecurityDeclarations(ISecurityDeclarationProvider provider)
   at Mono.Cecil.ImmediateModuleReader.ReadMethods(TypeDefinition type)
   at Mono.Cecil.ImmediateModuleReader.ReadType(TypeDefinition type)
   at Mono.Cecil.ImmediateModuleReader.ReadTypes(Collection`1 types)
   at Mono.Cecil.ImmediateModuleReader.ReadModule(ModuleDefinition module, Boolean resolve_attributes)
   at Mono.Cecil.ImmediateModuleReader.<ReadModule>b__2_0(ModuleDefinition module, MetadataReader reader)
   at Mono.Cecil.ModuleDefinition.Read[TItem,TRet](TItem item, Func`3 read)
   at Mono.Cecil.ImmediateModuleReader.ReadModule()
   at Mono.Cecil.ModuleReader.CreateModule(Image image, ReaderParameters parameters)
   at Mono.Cecil.ModuleDefinition.ReadModule(String fileName, ReaderParameters parameters)
   at Mono.Cecil.AssemblyDefinition.ReadAssembly(String fileName, ReaderParameters parameters)
   at Unity.Cecil.Awesome.AssemblyLoader.Load(String name) in /Users/bokken/build/output/unity/il2cpp/Unity.Cecil.Awesome/AssemblyLoader.cs:line 84
   at System.Linq.Enumerable.SelectArrayIterator`2.MoveNext()
   at System.Collections.Generic.HashSet`1.UnionWith(IEnumerable`1 other)
   at System.Collections.Generic.HashSet`1..ctor(IEnumerable`1 collection, IEqualityComparer`1 comparer)
   at Unity.IL2CPP.Common.AssemblyCollector.CollectAssembliesRecursive(IEnumerable`1 assemblies, IAssemblyLoader assemblyLoader, AssemblyDependenciesComponent assemblyDependencies) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.Common/AssemblyCollector.cs:line 25
   at Unity.IL2CPP.Common.AssemblyCollector.CollectAssembliesToConvert(NPath[] assemblyPaths, IAssemblyLoader assemblyLoader, AssemblyDependenciesComponent assemblyDependencies) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP.Common/AssemblyCollector.cs:line 15
   at Unity.IL2CPP.AssemblyConversion.Phases.InitializePhase.Run(AssemblyConversionContext context) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP/AssemblyConversion/Phases/InitializePhase.cs:line 18
   at Unity.IL2CPP.AssemblyConversion.Classic.ClassicConverter.Run(AssemblyConversionContext context) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP/AssemblyConversion.Classic/ClassicConverter.cs:line 11
   at Unity.IL2CPP.AssemblyConversion.AssemblyConverter.ConvertAssemblies(AssemblyConversionInputData data, AssemblyConversionParameters parameters, AssemblyConversionInputDataForTopLevelAccess dataForTopLevel) in /Users/bokken/build/output/unity/il2cpp/Unity.IL2CPP/AssemblyConversion/AssemblyConverter.cs:line 21
UnityEditorInternal.Runner.RunProgram (UnityEditor.Utils.Program p, System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser) (at /Users/bokken/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildUtils.cs:129)
UnityEditorInternal.Runner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, System.Action`1[T] setupStartInfo) (at /Users/bokken/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildUtils.cs:65)
UnityEditorInternal.IL2CPPBuilder.RunIl2CppWithArguments (System.Collections.Generic.List`1[T] arguments, System.Action`1[T] setupStartInfo, System.String generatedCppOutputDirectory) (at /Users/bokken/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:755)
UnityEditorInternal.IL2CPPBuilder.ConvertPlayerDlltoCpp (UnityEditor.Il2Cpp.Il2CppBuildPipelineData data, System.String outputDirectory, System.Boolean platformSupportsManagedDebugging) (at /Users/bokken/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:727)
UnityEditorInternal.IL2CPPBuilder.Run () (at /Users/bokken/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:560)
UnityEditorInternal.IL2CPPUtils.RunIl2Cpp (System.String tempFolder, System.String stagingAreaData, UnityEditorInternal.IIl2CppPlatformProvider platformProvider, System.Action`1[T] modifyOutputBeforeCompile, UnityEditor.RuntimeClassRegistry runtimeClassRegistry) (at /Users/bokken/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:231)
UnityEditor.iOS.PostProcessiPhonePlayer.CrossCompileManagedDlls (UnityEditor.iOS.PostProcessiPhonePlayer+BuildSettings bs, UnityEditor.iOS.PostProcessiPhonePlayer+ProjectPaths paths, UnityEditor.AssemblyReferenceChecker checker, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport buildReport) (at /Users/bokken/buildslave/unity/build/PlatformDependent/iPhonePlayer/Extensions/Common/BuildPostProcessor.cs:908)
UnityEditor.iOS.PostProcessiPhonePlayer.PostProcess (UnityEditor.iOS.PostProcessiPhonePlayer+BuildSettings bs, UnityEditor.iOS.PostProcessiPhonePlayer+ProjectPaths paths, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport buildReport) (at /Users/bokken/buildslave/unity/build/PlatformDependent/iPhonePlayer/Extensions/Common/BuildPostProcessor.cs:718)
UnityEditor.iOS.PostProcessiPhonePlayer.PostProcess (UnityEditor.iOS.PostProcessorSettings postProcessorSettings, UnityEditor.Modules.BuildPostProcessArgs args) (at /Users/bokken/buildslave/unity/build/PlatformDependent/iPhonePlayer/Extensions/Common/BuildPostProcessor.cs:663)
UnityEditor.iOS.iOSBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args) (at /Users/bokken/buildslave/unity/build/PlatformDependent/iPhonePlayer/Extensions/Common/ExtensionModule.cs:45)
Rethrow as BuildFailedException: Exception of type 'UnityEditor.Build.BuildFailedException' was thrown.
UnityEditor.iOS.iOSBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args) (at /Users/bokken/buildslave/unity/build/PlatformDependent/iPhonePlayer/Extensions/Common/ExtensionModule.cs:49)
UnityEditor.Modules.DefaultBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args, UnityEditor.BuildProperties& outProperties) (at /Users/bokken/buildslave/unity/build/Editor/Mono/Modules/DefaultBuildPostprocessor.cs:29)
UnityEditor.PostprocessBuildPlayer.Postprocess (UnityEditor.BuildTargetGroup targetGroup, UnityEditor.BuildTarget target, System.String installPath, System.String companyName, System.String productName, System.Int32 width, System.Int32 height, UnityEditor.BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport report) (at /Users/bokken/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:337)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&) (at /Users/bokken/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:189)

対処方法1

Assets 直下に下記ファイル link.xml を置く。

<linker>
    <assembly fullname="netstandard" preserve="all"/>
</linker>

その他

CascadeClassifier haarCascade = new CascadeClassifier("Assets/OpenCV+Unity/Demo/Face_Detector/haarcascade_frontalface_default.xml");

で顔検出したい場合は Assets/StreamingAssets 下に haarcascade_frontalface_default.xml を置いて

CascadeClassifier haarCascade = new CascadeClassifier(Application.streamingAssetsPath + "/haarcascade_frontalface_default.xml");

で指定しれば iOS 上でも顔検出が可能。