I have an AVQueuePlayer that gets songs from a Firebase Storage via their URL and plays them in sequence.
static func playQueue() {
for song in songs {
guard let url = song.url else { return }
lofiSongs.append(AVPlayerItem(url: url))
}
if queuePlayer == nil {
queuePlayer = AVQueuePlayer(items: lofiSongs)
} else {
queuePlayer?.removeAllItems()
lofiSongs.forEach { queuePlayer?.insert($0, after: nil) }
}
queuePlayer?.seek(to: .zero) // In case we added items back in
queuePlayer?.play()
}
And this works great.
I can also make the lock screen controls appear and use the play pause button like this:
private static func setRemoteControlActions() {
let commandCenter = MPRemoteCommandCenter.shared()
// Add handler for Play Command
commandCenter.playCommand.addTarget { [self] event in
queuePlayer?.play()
return .success
}
// Add handler for Pause Command
commandCenter.pauseCommand.addTarget { [self] event in
if queuePlayer?.rate == 1.0 {
queuePlayer?.pause()
return .success
}
return .commandFailed
}
}
The problem comes with setting the metadata of the player (name, image, etc).
I know it can be done once by setting MPMediaItemPropertyTitle and MPMediaItemArtwork, but how would I change it when the next track loads?
I'm not sure if my approach works for AVQueueplayer, but for playing live streams with AVPlayer you can "listen" to metadata receiving.
extension ViewController: AVPlayerItemMetadataOutputPushDelegate {
func metadataOutput(_ output: AVPlayerItemMetadataOutput, didOutputTimedMetadataGroups groups: [AVTimedMetadataGroup], from track: AVPlayerItemTrack?) {
//look for metadata in groups
}
}
I added the AVPlayerItemMetadataOutputPushDelegate via an extension to my ViewController.
I also found this post.
I hope this gives you a lead to a solution. As said I'm not sure how this works with AVQueuePlayer.
Related
I'm a student studying iOS development currently working on a simple AI project that utilizes SNAudioStreamAnalyzer to classify an incoming audio stream from the device's microphone. I can start the stream and analyze audio no problem, but I've noticed I can't seem to get my app to stop analyzing and close the audio input stream when I'm done. At the beginning, I initialize the audio engine and create the classification request like so:
private func startAudioEngine() {
do {
// start the stream of audio data
try audioEngine.start()
let snoreClassifier = try? SnoringClassifier2_0().model
let classifySoundRequest = try audioAnalyzer.makeRequest(snoreClassifier)
try streamAnalyzer.add(classifySoundRequest,
withObserver: self.audioAnalyzer)
} catch {
print("Unable to start AVAudioEngine: \(error.localizedDescription)")
}
}
After I'm done classifying my audio stream, I attempt to stop the audio engine and close the stream like so:
private func terminateNight() {
streamAnalyzer.removeAllRequests()
audioEngine.stop()
stopAndSaveNight()
do {
let session = AVAudioSession.sharedInstance()
try session.setActive(false)
} catch {
print("unable to terminate audio session")
}
nightSummary = true
}
However, after I call the terminateNight() function my app will continue using the microphone and classifying the incoming audio. Here's my SNResultsObserving implementation:
class AudioAnalyzer: NSObject, SNResultsObserving {
var prediction: String?
var confidence: Double?
let snoringEventManager: SnoringEventManager
internal init(prediction: String? = nil, confidence: Double? = nil, snoringEventManager: SnoringEventManager) {
self.prediction = prediction
self.confidence = confidence
self.snoringEventManager = snoringEventManager
}
func makeRequest(_ customModel: MLModel? = nil) throws -> SNClassifySoundRequest {
if let model = customModel {
let customRequest = try SNClassifySoundRequest(mlModel: model)
return customRequest
} else {
throw AudioAnalysisErrors.ModelInterpretationError
}
}
func request(_ request: SNRequest, didProduce: SNResult) {
guard let classificationResult = didProduce as? SNClassificationResult else { return }
let topClassification = classificationResult.classifications.first
let timeRange = classificationResult.timeRange
self.prediction = topClassification?.identifier
self.confidence = topClassification?.confidence
if self.prediction! == "snoring" {
self.snoringEventManager.snoringDetected()
} else {
self.snoringEventManager.nonSnoringDetected()
}
}
func request(_ request: SNRequest, didFailWithError: Error) {
print("ended with error \(didFailWithError)")
}
func requestDidComplete(_ request: SNRequest) {
print("request finished")
}
}
It was my understanding that upon calling streamAnalyzer.removeAllRequests() and audioEngine.stop() the app would stop streaming from the microphone and call the requestDidComplete function, but this isn't the behavior I'm getting. Any help is appreciated!
From OP's edition:
So I've realized it was a SwiftUI problem. I was calling the startAudioEngine() function in the initializer of the view it was declared on. I thought this would be fine, but since this view was embedded in a parent view when SwiftUI updated the parent it was re-initializing my view and as such calling startAudioEngine() again. The solution was to call this function in on onAppear block so that it activates the audio engine only when the view appears, and not when SwiftUI initializes it.
I don't believe you should expect to receive requestDidComplete due to removing a request. You'd expect to receive that when you call completeAnalysis.
I have an AVPlayer object, and I'm observing the state changes using KVO; Changes to .timeControlStatus, which tells you whether the AVPlayer is playing, stopped, loading, or paused.
The problem is the AVPlayer sets the .timeControlStatus property to .waitingToPlayAtSpecifiedRate (means the file is loading) many, many times while the file is loading. I only want to be notified on the first change to loading, not subsequent settings. My observer is set up like this:
// watch .timeControlStatus
playerStatusToken = player?.observe(\.timeControlStatus, options: [.new], changeHandler: { [weak self] player, change in
if player.timeControlStatus == AVPlayer.TimeControlStatus.paused {
if self?.playerItemActive == false {
print("playback stopped")
self?.prevID = self!.currentID
self?.currentID = 0
self?.currentURL = nil
self?.playState = .stopped
}
else {
print("playback paused")
self?.playState = .paused
}
}
else if player.timeControlStatus == AVPlayer.TimeControlStatus.playing {
self?.playState = .playing
}
else if player.timeControlStatus == AVPlayer.TimeControlStatus.waitingToPlayAtSpecifiedRate {
self?.playState = .loading
}
})
Is there a way I can only respond to changes? I don't wan't to know if the .timeControlStatus is set to the same value as last time. Is there a way to do that (aside from keeping a variable called "lastStatus", and comparing to that).
Using Combine allows you to observe changes and filter out duplicate values out of the box
// retain var in your class
var cancellable: Cancellable?
// observe changes
cancellable = player?.publisher(for: \.timeControlStatus)
.removeDuplicates()
.sink() {
// your change handler
}
I am writing a Safari app extension and want to fetch the URL for the active page in my view controller.
This means nested completion handlers to fetch the window, to fetch the tab, to fetch the page, to access its properties. Annoying but simple enough. It looks like this:
func doStuffWithURL() {
var url: URL?
SFSafariApplication.getActiveWindow { (window) in
window?.getActiveTab { (tab) in
tab?.getActivePage { (page) in
page?.getPropertiesWithCompletionHandler { (properties) in
url = properties?.url
}
}
}
}
// NOW DO STUFF WITH THE URL
NSLog("The URL is \(String(describing: url))")
}
The obvious problem is it does not work. Being completion handlers they will not be executed until the end of the function. The variable url will be nil, and the stuff will be done before any attempt is made to get the URL.
One way around this is to use a DispatchQueue. It works, but the code is truly ugly:
func doStuffWithURL() {
var url: URL?
let group = DispatchGroup()
group.enter()
SFSafariApplication.getActiveWindow { (window) in
if let window = window {
group.enter()
window.getActiveTab { (tab) in
if let tab = tab {
group.enter()
tab.getActivePage { (page) in
if let page = page {
group.enter()
page.getPropertiesWithCompletionHandler { (properties) in
url = properties?.url
group.leave()
}
}
group.leave()
}
}
group.leave()
}
}
group.leave()
}
// NOW DO STUFF WITH THE URL
group.notify(queue: .main) {
NSLog("The URL is \(String(describing: url))")
}
}
The if blocks are needed to know we are not dealing with a nil value. We need to be certain a completion handler will return, and therefore a .leave() call before we can call a .enter() to end up back at zero.
I cannot even bury all that ugliness away in some kind of getURLForPage() function or extension (adding some kind of SFSafariApplication.getPageProperties would be my preference) as obviously you cannot return from a function from within a .notify block.
Although I tried creating a function using queue.wait and a different DispatchQueue as described in the following answer to be able to use return…
https://stackoverflow.com/a/42484670/2081620
…not unsurprisingly to me it causes deadlock, as the .wait is still executing on the main queue.
Is there a better way of achieving this? The "stuff to do," incidentally, is to update the UI at a user request so needs to be on the main queue.
Edit: For the avoidance of doubt, this is not an iOS question. Whilst similar principles apply, Safari app extensions are a feature of Safari for macOS only.
Thanks to Larme's suggestions in the comments, I have come up with a solution that hides the ugliness, is reusable, and keep the code clean and standard.
The nested completion handlers can be replaced by an extension to the SFSafariApplication class so that only one is required in the main body of the code.
extension SFSafariApplication {
static func getActivePageProperties(_ completionHandler: #escaping (SFSafariPageProperties?) -> Void) {
self.getActiveWindow { (window) in
guard let window = window else { return completionHandler(nil) }
window.getActiveTab { (tab) in
guard let tab = tab else { return completionHandler(nil) }
tab.getActivePage { (page) in
guard let page = page else { return completionHandler(nil) }
page.getPropertiesWithCompletionHandler { (properties) in
return completionHandler(properties)
}
}
}
}
}
}
Then in the code it can be used as:
func doStuffWithURL() {
SFSafariApplication.getActivePageProperties { (properties) in
if let url = properties?.url {
// NOW DO STUFF WITH THE URL
NSLog("URL is \(url))")
} else {
// NOW DO STUFF WHERE THERE IS NO URL
NSLog("URL ERROR")
}
}
}
I'm trying to use Apple's AVMIDIPlayer object for playing a MIDI file. It seems easy enough in Swift, using the following code:
let midiFile:NSURL = NSURL(fileURLWithPath:"/path/to/midifile.mid")
var midiPlayer: AVMIDIPlayer?
do {
try midiPlayer = AVMIDIPlayer(contentsOf: midiFile as URL, soundBankURL: nil)
midiPlayer?.prepareToPlay()
} catch {
print("could not create MIDI player")
}
midiPlayer?.play {
print("finished playing")
}
And it plays for about 0.05 seconds. I presume I need to frame it in some kind of loop. I've tried a simple solution:
while stillGoing {
midiPlayer?.play {
let stillGoing = false
}
}
which works, but ramps up the CPU massively. Is there a better way?
Further to the first comment, I've tried making a class, and while it doesn't flag any errors, it doesn't work either.
class midiPlayer {
var player: AVMIDIPlayer?
func play(file: String) {
let myURL = URL(string: file)
do {
try self.player = AVMIDIPlayer.init(contentsOf: myURL!, soundBankURL: nil)
self.player?.prepareToPlay()
} catch {
print("could not create MIDI player")
}
self.player?.play()
}
func stop() {
self.player?.stop()
}
}
// main
let myPlayer = midiPlayer()
let midiFile = "/path/to/midifile.mid"
myPlayer.play(file: midiFile)
You were close with your loop. You just need to give the CPU time to go off and do other things instead of constantly checking to see if midiPlayer is finished yet. Add a call to usleep() in your loop. This one checks every tenth of a second:
let midiFile:NSURL = NSURL(fileURLWithPath:"/Users/steve/Desktop/Untitled.mid")
var midiPlayer: AVMIDIPlayer?
do {
try midiPlayer = AVMIDIPlayer(contentsOfURL: midiFile, soundBankURL: nil)
midiPlayer?.prepareToPlay()
} catch {
print("could not create MIDI player")
}
var stillGoing = true
while stillGoing {
midiPlayer?.play {
print("finished playing")
stillGoing = false
}
usleep(100000)
}
You need to ensure that the midiPlayer object exists until it's done playing. If the above code is just in a single function, midiPlayer will be destroyed when the function returns because there are no remaining references to it. Typically you would declare midiPlayer as a property of an object, like a subclassed controller.
Combining Brendan and Steve's answers, the key is sleep or usleep and sticking the play method outside the loop to avoid revving the CPU.
player?.play({return})
while player!.isPlaying {
sleep(1) // or usleep(10000)
}
The original stillGoing value works, but there is also an isPlaying method.
.play needs something between its brackets to avoid hanging forever after completion.
Many thanks.
I am following instructions here, I've put together this test project to handle interruptions to audio play. Specifically, I'm using the alarm from the default iphone clock app as interruption. It appears that the interruption handler is getting called but is not getting past the let = interruptionType line as "wrong type" showed up twice.
import UIKit
import AVFoundation
class ViewController: UIViewController {
var player = AVAudioPlayer()
let audioPath = NSBundle.mainBundle().pathForResource("rachmaninov-romance-sixhands-alianello", ofType: "mp3")!
func handleInterruption(notification: NSNotification) {
guard let interruptionType = notification.userInfo?[AVAudioSessionInterruptionTypeKey] as? AVAudioSessionInterruptionType else { print("wrong type"); return }
switch interruptionType {
case .Began:
print("began")
// player is paused and session is inactive. need to update UI)
player.pause()
print("audio paused")
default:
print("ended")
/**/
if let option = notification.userInfo?[AVAudioSessionInterruptionOptionKey] as? AVAudioSessionInterruptionOptions where option == .ShouldResume {
// ok to resume playing, re activate session and resume playing
// need to update UI
player.play()
print("audio resumed")
}
/**/
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
do {
try player = AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: audioPath))
player.numberOfLoops = -1 // play indefinitely
player.prepareToPlay()
//player.delegate = player
} catch {
// process error here
}
// enable play in background https://stackoverflow.com/a/30280699/1827488 but this audio still gets interrupted by alerts
do {
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
print("AVAudioSession Category Playback OK")
do {
try AVAudioSession.sharedInstance().setActive(true)
print("AVAudioSession is Active")
} catch let error as NSError {
print(error.localizedDescription)
}
} catch let error as NSError {
print(error.localizedDescription)
}
// add observer to handle audio interruptions
// using 'object: nil' does not have a noticeable effect
let theSession = AVAudioSession.sharedInstance()
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ViewController.handleInterruption(_:)), name: AVAudioSessionInterruptionNotification, object: theSession)
// start playing audio
player.play()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Furthermore, following an idea here, I have modified the handler to
func handleInterruption(notification: NSNotification) {
//guard let interruptionType = notification.userInfo?[AVAudioSessionInterruptionTypeKey] as? AVAudioSessionInterruptionType else { print("wrong type"); return }
if notification.name != AVAudioSessionInterruptionNotification
|| notification.userInfo == nil{
return
}
var info = notification.userInfo!
var intValue: UInt = 0
(info[AVAudioSessionInterruptionTypeKey] as! NSValue).getValue(&intValue)
if let interruptionType = AVAudioSessionInterruptionType(rawValue: intValue) {
switch interruptionType {
case .Began:
print("began")
// player is paused and session is inactive. need to update UI)
player.pause()
print("audio paused")
default:
print("ended")
/** /
if let option = notification.userInfo?[AVAudioSessionInterruptionOptionKey] as? AVAudioSessionInterruptionOptions where option == .ShouldResume {
// ok to resume playing, re activate session and resume playing
// need to update UI
player.play()
print("audio resumed")
}
/ **/
player.play()
print("audio resumed")
}
}
}
Results are that all of "began", "audio paused", "ended" and "audio resumed" show up in console but audio play is not actually resumed.
Note: I moved the player.play() outside of the commented out where option == .ShouldResume if statement because that if condition is not true when the .Ended interruption occurs.
(Posted on behalf of the question author, after it was posted in the question).
Solution found! Following discussion here, inserted this in viewDidLoad()
do {
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, withOptions: AVAudioSessionCategoryOptions.MixWithOthers)
} catch {
}
After clicking "ok" on the alarm interruption, the audio play continued. Unlike previously noted, the solution does NOT require an interruption handler (which #Leo Dabus has since removed).
However if you are using an interruption handler, .play() must NOT be invoked within handleInterruption() as doing so does NOT guarantee play to resume & seems to prevent audioPlayerEndInterruption() to be called (see docs). Instead .play() must be invoked within audioPlayerEndInterruption() (any of its 3 versions) to guarantee resumption.
Furthermore, AVAudioSession must be give option .MixWithOthers noted by #Simon Newstead if you want your app to resume play after interruption when your app is in the background. It seems that if a user wants the app to continue playing when it goes into the background, it is logical to assume the user also wants the app to resume playing after an interruption while the app is in the background. Indeed that is the behaviour exhibited by the Apple Music app.
#rockhammers suggestion worked for me. Here
before class
let theSession = AVAudioSession.sharedInstance()
in viewDidLoad
NotificationCenter.default.addObserver(self, selector: #selector(ViewController.handleInterruption(notification:)), name: NSNotification.Name.AVAudioSessionInterruption, object: theSession)
And then the Function
func handleInterruption(notification: NSNotification) {
print("handleInterruption")
guard let value = (notification.userInfo?[AVAudioSessionInterruptionTypeKey] as? NSNumber)?.uintValue,
let interruptionType = AVAudioSessionInterruptionType(rawValue: value)
else {
print("notification.userInfo?[AVAudioSessionInterruptionTypeKey]", notification.userInfo?[AVAudioSessionInterruptionTypeKey])
return }
switch interruptionType {
case .began:
print("began")
vox.pause()
music.pause()
print("audioPlayer.playing", vox.isPlaying)
/**/
do {
try theSession.setActive(false)
print("AVAudioSession is inactive")
} catch let error as NSError {
print(error.localizedDescription)
}
pause()
default :
print("ended")
if let optionValue = (notification.userInfo?[AVAudioSessionInterruptionOptionKey] as? NSNumber)?.uintValue, AVAudioSessionInterruptionOptions(rawValue: optionValue) == .shouldResume {
print("should resume")
// ok to resume playing, re activate session and resume playing
/**/
do {
try theSession.setActive(true)
print("AVAudioSession is Active again")
vox.play()
music.play()
} catch let error as NSError {
print(error.localizedDescription)
}
play()
}
}
}
some reasons interruptionNotification is not working correctly on iOS 12.x So I added silenceSecondaryAudioHintNotification
With alarm notification incoming, you can try to use silenceSecondaryAudioHintNotification.
#objc func handleSecondaryAudioSilence(notification: NSNotification) {
guard let userInfo = notification.userInfo,
let typeValue = userInfo[AVAudioSessionSilenceSecondaryAudioHintTypeKey] as? UInt,
let type = AVAudioSession.SilenceSecondaryAudioHintType(rawValue: typeValue) else {
return
}
if type == .end {
// Other app audio stopped playing - restart secondary audio.
reconnectAVPlayer()
}
}