I have an array of audio instructions that I would like to randomize, play (one at a time), and do some data recording in between each instruction.

With the below code, I have a button press that triggers beginTest(), but the instruction tracks play simultaneously. It never gets to startRecord().

I've tried placing startRecord() inside audioPlayerDidFinishPlaying; in that case it does get to startRecord() for the first track, but doesn't continue to the next iteration of the loop inside beginTest() where playScript() is called.

func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool)
{
    self.player = nil
    print("finished playing this file")

}

func playScript(c: String)
{
    let path = Bundle.main.path(forResource: c, ofType:"m4a")!
    let url = URL(fileURLWithPath: path)

    do {
        self.player = try AVAudioPlayer(contentsOf: url)
        self.player?.delegate = self
        self.player?.play()
        print(c)
        print("playing script for "   c)
    } catch {
        print("couldn't load script")
    }
}

func beginTest()
{
    for c in conditions.shuffled()
    {
        playScript(c: c)
        
        if self.player == nil
        {
            startRecord()
            print("started data recording")
        }
    }
    
    exportData()
}

I'm guessing that beginTest() keeps moving along the for loop before audioPlayerDidFinishPlaying resets the player to nil, but I don't know how to stall this.

CodePudding user response：

The approach using audioPlayerDidFinishPlaying(_:,successfully:) is correct. In your code when you call playScript(c:) you will iterate through all audio files from conditions array and call startRecord method really quickly, while first audio is playing. All sounds will be placed in a queue and play one by one. I don't know contents of startRecord method, but I don't think that it was supposed to be called like that.

In order to avoid those problems you need to call playScript(c:) and then wait for method startRecord() to finish, and then call playScript(c:) again. So you can try something like this:

import AVFoundation

class SomeClass: NSObject, AVAudioPlayerDelegate {
    
    var player: AVAudioPlayer?
    var conditions = [String]()
    var instructions: [() -> ()] = []
        
    func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
        print("finished playing \(player.url)")
        startRecord {
            playNextInstruction()
        }
    }

    func playScript(c: String)
    {
        let path = Bundle.main.path(forResource: c, ofType:"m4a")!
        let url = URL(fileURLWithPath: path)

        do {
            self.player = try AVAudioPlayer(contentsOf: url)
            self.player?.delegate = self
            self.player?.play()
            print(c)
            print("playing script for "   c)
        } catch {
            print("couldn't load script")
        }
    }

    func beginTest() {
        instructions = conditions.shuffled().map { [unowned self] condition in
            return {
                self.playScript(c: condition)
            }
        }
        playNextInstruction()
    }
    
    func playNextInstruction() {
        if instructions.count != 0 {
            instructions.remove(at: 0)()
        } else {
            exportData()
        }
    }
    
    func exportData() {
    
    }
    
    func startRecord(completion: (() -> ())) {
        
    }
        
}

If it won't work then I suggest to try searching problem somewhere else in your code.