How to pass IRuntimePtr to another function?

In my ARMNN network initialization routine I am creating an ARMNN runtime like this:

    armnn::IRuntimePtr runtime = armnn::IRuntime::Create(armnn::IRuntime::CreationOptions());

    armnn::IOptimizedNetworkPtr optNet = Optimize(*network, backends, runtime->GetDeviceSpec(), armnn::OptimizerOptions());

    runtime->LoadNetwork(networkId, std::move(optNet), errorMessage);

I need to run the network in another C++ function.  How can I pass the runtime pointer to that other function?  Or, is there a way for the other function to retrieve the pointer to the runtime?