I have the following function to process audio data in Obj-C (and then deeper in C++):

- (void) audioProcess: (int) numChannels
           numSamples: (int) numSamples
               stride: (int) stride
                 data: (float * const *) data;

This signature is classic for processing audio buffer data stored in contiguous memory. It could be interleaved or not, depending on the buffer.

Then in Swift, I want to process an audio buffer like so:

let buffer = ... // get AVAudioPCMBuffer from somewhere

if let floatChannelData = buffer.floatChannelData {

    audioProcess(Int32(buffer.format.channelCount),
                 numSamples: Int32(buffer.frameLength),
                 stride: Int32(buffer.stride),
                 data: floatChannelData)
}

I get the following compilation error:

• Cannot convert value of type 'UnsafePointer<UnsafeMutablePointer<Float>>' to expected argument type 'UnsafePointer<UnsafeMutablePointer<Float>?>'

Notice the difference in optionality of the UnsafeMutablePointer<Float>.

How can I pass the floatChannelData from Swift to Obj-C (C++)?

Edit: typos