I'm developing a game that will use speech recognition to execute various commands. I am using code from Apple's Recognizing Speech in Live Audio documentation page.
When I run this in a Swift Playground, it works just fine. However, when I make a SpriteKit game application (basic setup from Xcode's "New Project" menu option), I get the following error:
required condition is false: IsFormatSampleRateAndChannelCountValid(hwFormat)
Upon further research, it appears that my input node has no channels. The following is the relevant portion of my code, along with debug output:
let inputNode = audioEngine.inputNode
print("Number of inputs: \(inputNode.numberOfInputs)")
// 1
print("Input Format: \(inputNode.inputFormat(forBus: 0))")
// <AVAudioFormat 0x600001bcf200: 0 ch, 0 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved>
let channelCount = inputNode.inputFormat(forBus: 0).channelCount
print("Channel Count: \(channelCount)")
// 0 <== Agrees with the inputFormat output listed previously
// Configure the microphone input.
print("Number of outputs: \(inputNode.numberOfOutputs)")
// 1
let recordingFormat = inputNode.outputFormat(forBus: 0)
print("Output Format: \(recordingFormat)")
// <AVAudioFormat 0x600001bf3160: 2 ch, 44100 Hz, Float32, non-inter>
inputNode.installTap(onBus: 0, bufferSize: 256, format: recordingFormat, block: audioTap) // <== This is where the error occurs.
// NOTE: 'audioTap' is a function defined in this class. Using this defined function instead of an inline, anonymous function.
The code snippet is included in the game's AppDelegate class (which includes import statements for Cocoa, AVFoundation, and Speech), and executes during its applicationDidFinishLaunching function. I'm having trouble understanding why Playground works, but a game app doesn't work. Do I need to do something specific to get the application to recognize the microphone?
NOTE: This if for MacOS, NOT iOS. While the "How To" documentation cited earlier indicates iOS, Apple stated at WWDC19 that it is now supported on the MacOS.
NOTE: I have included the NSSpeechRecognitionUsageDescription key in the applications plist, and successfully acknowledged the authorization request for the microphone.
