iOS Targets

When building for iOS, the trueSpatial plug-ins require some additional configuration to work correctly.

In comparison to the Unity counterpart, the FMOD integration for Unreal Engine doesn’t provide an interface to load plug-ins from static libraries, and dynamic libraries are not supported on iOS.

To work around this limitation, the source code of the FMOD integration needs to be modified to include the trueSpatial plug-ins directly.

Add the Accelerate Framework

To use the trueSpatial plug-ins on iOS, the Accelerate framework needs to be linked to the FMOD Studio module. To do this, add the following highlighted code to the FMODStudio.Build.cs file:

<project>/Plugins/FMODStudio/Source/FMODStudio/FMODStudio.build.cs


public FMODStudio(ReadOnlyTargetRules Target) : base(Target)
{
    if (Target.Platform == UnrealTargetPlatform.IOS)
    {
        PublicFrameworks.Add("Accelerate");
    }
 
    PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs;
    PrivatePCHHeaderFile = "Private/FMODStudioPrivatePCH.h";
 
// ...

Declare symbols to load

In order to call the plug-in descriptions functions during initialization, the functions need to be declared in the FMODStudioModule.cpp file. Add the following highlighted code to the FMODStudioModule.cpp file, e.g. right before the CreateStudioSystem function:

<project>/Plugins/FMODStudio/Source/FMODStudio/Private/FMODStudioModule.cpp


#if PLATFORM_IOS
extern "C" {
FMOD_DSP_DESCRIPTION* F_CALL FMOD_atmoky_Spatializer_GetDSPDescription();
FMOD_DSP_DESCRIPTION* F_CALL FMOD_atmoky_Renderer_GetDSPDescription();
FMOD_DSP_DESCRIPTION* F_CALL FMOD_atmoky_AmbisonicRenderer_GetDSPDescription();
FMOD_DSP_DESCRIPTION* F_CALL FMOD_atmoky_Externalizer_GetDSPDescription();
}
#endif
 
void FFMODStudioModule::CreateStudioSystem(EFMODSystemContext::Type Type)
{
// ...

With this the linker will know to look for these functions outside of the FMOD integration.

Register the plug-ins during initialization

To register the trueSpatial plug-ins during initialization, add the following highlighted code to the CreateStudioSystem function in the FMODStudioModule.cpp file, e.g. right after the LoadPlugin loop:

<project>/Plugins/FMODStudio/Source/FMODStudio/Private/FMODStudioModule.cpp


void FFMODStudioModule::CreateStudioSystem(EFMODSystemContext::Type Type)
{
// ...
    for (FString PluginName : Settings.PluginFiles)
    {
        if (!PluginName.IsEmpty())
            LoadPlugin(Type, *PluginName);
    }
 
    unsigned int handle = 0;
    lowLevelSystem->registerDSP(FMOD_atmoky_Spatializer_GetDSPDescription(), &handle);
    lowLevelSystem->registerDSP(FMOD_atmoky_Renderer_GetDSPDescription(), &handle);
    lowLevelSystem->registerDSP(FMOD_atmoky_AmbisonicRenderer_GetDSPDescription(), &handle);
    lowLevelSystem->registerDSP(FMOD_atmoky_Externalizer_GetDSPDescription(), &handle);
 
    if (Type == EFMODSystemContext::Runtime)
    {
        // ...

With this configuration, the trueSpatial plug-ins should work correctly on iOS. In case you update the FMOD integration, you might need to reapply these changes.