You will need an interruption state variable that is referenced in the completion handler and toggled by the interrupting code. Here's some shorthand code that makes some assumptions on how you're looping through buffers:
var node: AVAudioPlayerNode!
var loopingBuffers: [AVAudioPCMBuffer] = [buffer1, buffer2, buffer3]
var interruptBuffers = false // state variable to handle the interruption
func scheduleNextBuffer() {
/* code to find the next buffer in the loopingBuffers queue */
// assuming you have instantiated an AVAudioPlayerNode elsewhere
node.scheduleBuffer(nextBuffer, completionHandler: bufferCompletion)
}
func bufferCompletion() {
// check the state variable to make certain the completionHandler isn't being triggered by a scheduling interruption
guard !interruptBuffers else { return }
scheduleNextBuffer()
}
func interruptBuffers() {
let newBuffers: [AVAudioPCMBuffer] = [buffer4, buffer5, buffer6]
interruptBuffers = true
node.scheduleBuffer(buffer4, at: nil, options: .interrupts, completionHandler: bufferCompletion)
// cleanup your state and queue up your new buffers
interruptBuffers = false
loopingBuffers = newBuffers
}