Question Encrypt il2cpp's global-metadata.dat,but not work on ios

I want to encrypt the file global-metadata.dat, So I encrypt it after the xcode and Android project was exported.Then I modify MetadataLoader.cpp in unity installed folder.The path is:
android：\Editor\Data\il2cpp\libil2cpp\vm\MetadataLoader.cpp
Mac：Unity.app\Contents\il2cpp\libil2cpp\vm\MetadataLoader.cpp
I add decryption code in the function LoadMetadataFile
It works well on Android,but it doesn't work on ios. It's like the decryption code never runs.Why?

Code (CSharp):

1. void* MetadataLoader::LoadMetadataFile(const char* fileName)
2. {
3.     std::string resourcesDirectory = utils::PathUtils::Combine(utils::Runtime::GetDataDir(), utils::StringView<char>("Metadata"));
4.  
5.     std::string resourceFilePath = utils::PathUtils::Combine(resourcesDirectory, utils::StringView<char>(fileName, strlen(fileName)));
6.  
7.     int error = 0;
8.     FileHandle* handle = File::Open(resourceFilePath, kFileModeOpen, kFileAccessRead, kFileShareRead, kFileOptionsNone, &error);
9.     if (error != 0)
10.         return NULL;
11.  
12.     void* fileBuffer = utils::MemoryMappedFile::Map(handle);
13.  
14.     File::Close(handle, &error);
15.     if (error != 0)
16.     {
17.         utils::MemoryMappedFile::Unmap(fileBuffer);
18.         fileBuffer = NULL;
19.         return NULL;
20.     }
21.     // decryption code
22.     int64_t length = utils::MemoryMappedFile::GetLength(fileBuffer);
23.     char* data = (char*)malloc(length);
24.     memcpy(data, fileBuffer, length);
25.     char* result = MetadataLoader::DecryptFile(data, length);
26.     return (void*)result;
27.     //return fileBuffer;
28. }

 

When building for the iOS target, a precompiled version of libil2cpp (that is "Libraries/libil2cpp.a" in your generated XCode project) is used instead of building libil2cpp from source, so I'd say there is no quick or easy way to overcome this.