Swift need closure for audioplayer - ios

Question

I am building an app with several view controllers. I need to control music from all of them so I have created a dedicated music class which I use to setup / play / stop / pause.
I have recorded audio questions and answers and I need to be able to play the question and then the answer mp3 files.
So I believe that here a few way to accomplish this delegate and protocols, using the func audioPlayerDidFinishPlaying and using closures. From what I can understand closures are the best option for what I am trying to achieve.
My starting point in the MakeMusic Class is:
class MakeMusicClass : NSObject, AVAudioPlayerDelegate {
static let shared = MakeMusicClass()
var audioPlayer = AVAudioPlayer()
override init() { }
func setup(Selection: String) {
do {
audioPlayer = try AVAudioPlayer(contentsOf: URL.init(fileURLWithPath: Bundle.main.path(forResource: Selection, ofType: "mp3")!))
audioPlayer.prepareToPlay()
audioPlayer.delegate=self
} catch {
print (error)
}
}
func play() {
audioPlayer.play()
}
My calling file is:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
MakeMusicClass.shared.setup(Selection: "Question11")
MakeMusicClass.shared.play()
MakeMusicClass.shared.setup(Selection: "Answer11")
MakeMusicClass.shared.play()
To get this working I understand that I need to add a closure to the called class:
func play() {
var closure = { in
audioPlayer.play()
}
}
And I need to update where I need to call the function something like:
override func viewDidLoad() {
super.viewDidLoad()
MakeMusicClass.shared.setup(Selection: "Question11")
MakeMusicClass.shared.play() {
MakeMusicClass.shared.setup(Selection: "Answer11")
MakeMusicClass.shared.play()
}
I have spent ages trying to get my head around this, but I am struggling. My code here is clearly not working as there is something fundamental that I am missing. I have tried passing void and parameters, but I don't understand what parameters should be passed. The closest I have come is using the audioPlayerDidFinishPlaying within the makemusic class trigger the next audio file, but I don't know that this is ideal.

Answer 1

I think your best bet will be in your MakeMusicClass taking an Array as an initialiser e.g. a question and and answer, and then use AVAudioPlayerDelegate to trigger the next file, which I think is what you are trying to get at (and very close ^________*).
For example:
class AudioLooper: NSObject, AVAudioPlayerDelegate {
var debugView = true
var audioLoopPlayer: AVAudioPlayer!
var audioFileIndex: Int = 0
var audioFileArray: [String] = []
//-------------------------------------------------
//MARK: Audio Player Initialisation & Functionality
//-------------------------------------------------
/// Function To Initialise The Audio Loop Player
///
/// - Parameter audioFiles: [String] - The Array Of Audio Files To Play
func initAudioPlayerWith(audioFiles: [String]) {
audioFileArray = audioFiles
if debugView { print("Audio Files To Play In Sequence == \(audioFileArray)") }
}
/// Function To Play An Array Of Audio Files
///
/// - Parameter index: (Int) - The Current Index Of The Audio Sequence
func playAudioLoopAt(index: Int) {
let currentAudioFile = "\(audioFileArray[audioFileIndex])"
if let audioFilePath = Bundle.main.path(forResource: currentAudioFile, ofType: "mp3"){
do {
let audioFileUrl = NSURL.fileURL(withPath: audioFilePath)
// Set An Instance Of AVAudioSession Which Allows Playback Even When Device Is Muted
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
try AVAudioSession.sharedInstance().setActive(true)
audioLoopPlayer = try AVAudioPlayer(contentsOf: audioFileUrl)
audioLoopPlayer.prepareToPlay()
audioLoopPlayer.delegate = self
audioLoopPlayer.play()
if debugView { print("Playing \(currentAudioFile) ") }
audioFileIndex += 1
} catch {
print("Error Playing Audio")
}
} else {
print("Error Finding File: \(currentAudioFile)")
}
}
/// Function To Continue The Audio Sequence
#objc func continueAudioLoop(){
playAudioLoopAt(index: audioFileIndex)
}
/// Function To Stop The Audio Looop Player
func stopAudioPlayer() {
if audioLoopPlayer != nil {
audioFileIndex=0
audioLoopPlayer.stop()
audioLoopPlayer = nil
}
}
//-----------------------------
//MARK: AVAudio Player Delegate
//-----------------------------
func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
if audioFileIndex < audioFileArray.count {
self.perform(#selector(continueAudioLoop), with: self, afterDelay: 0.5)
}else{
audioFileIndex=0
}
}
}
In my example you simply init like so:
audioLooper = AudioLooper()
audioLooper?.initAudioPlayerWith(audioFiles: ["question", "answer"])
audioLooper?.playAudioLoopAt(index: 0)
Where audioLooper is declared like so : var audioLooper:AudioLooper?
Clearly my example is not a Singleton, but it should give you an idea of how you can adjust your MakeMusicClass to make it fit...
You can also add a Delegate Method like so to inform the ViewController the audio has finished or perform some other task like update the next question etc e.g:
#objc protocol AudioLooperDelegate {
#objc optional func update()
}
Then in your ViewController:
var delegate: AudioLooperDelegate?
And in the AudioLooper Class you can then add the delegate method where needed e.g:
func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
if audioFileIndex < audioFileArray.count {
self.perform(#selector(continueAudioLoop), with: self, afterDelay: 0.5)
}else{
audioFileIndex=0
delegate?.updateUI!()
}
}
}