I need to be able to play a sound while running the application in the background.
I tried with UILocalNotifications but the file needs to be part of the bundle, and that will not be the case, as I need to generate the sound files on the fly...
So is there any way that I can play a sound while running in the background?
Thanks.
You can't, unless you continuously play audio and have the appropriate audio session category set for your app... then your app doesn't go to sleep, it continues to run (again so long as audio is playing).
This is part of the design limitations of iOS multitasking.
Apple has allowed people to get away with having a continuously looping blank audio file (AVAudioPlayer loop = -1 with a 1-sec blank CAF file) if the app is primarily audio related and it is obvious to the user that this has battery life implications (and can be disabled by the user), but YMMV... you app can also be rejected for this.
Related
I'm doing some audio streaming with iOS 7's Multipeer Connectivity framework. The streaming works well, but when I put the app on background it stops working.
Someone can tell me if this is a framework limitation, or I'm doing something wrong?
And, if it is a framework limitation, is it possible to do something to avoid this?
Can I use Background Tasks, to keep streaming and music working on background?
Is possible do this? If is not possible, do any alternatives exist for MultiPeer audio streaming between iOS devices?.
I´m using this example: https://github.com/tonyd256/TDAudioStreamer.
Explained on this page: http://robots.thoughtbot.com/streaming-audio-to-multiple-listeners-via-ios-multipeer-connectivity.
Thanks a lot!
On the Apple documentation for playing audio in the background (scroll down a bit). Some relevant paragraphs:
When the UIBackgroundModes key contains the audio value, the system’s media frameworks automatically prevent the corresponding app from being suspended when it moves to the background. As long as it is playing audio or video content or recording audio content, the app continues to run in the background. However, if recording or playback stops, the system suspends the app.
You can use any of the system audio frameworks to work with background audio content, and the process for using those frameworks is unchanged.
This means that iOS should recognize that you're playing audio through Core Audio, and keep your app unsuspended, as long as you've correctly configured your app for playing audio in the background.
Because your app is not suspended while playing media files, callbacks operate normally while your app is in the background. In your callbacks, though, you should do only the work necessary to provide data for playback. For example, a streaming audio app would need to download the music stream data from its server and push the current audio samples out for playback. Apps should not perform any extraneous tasks that are unrelated to playback.
You should be able to operate normally as long as your app is still playing audio, and is allowed to do what it needs to in order to continue playing audio. This means that you should be able to continue to use MPC in the background to receive the audio data and play it.
Be sure to read the entire documentation on the subject, especially regarding Audio Sessions.
iOS devices get limited cpu cycles for explicit purposes when they have been backgrounded by the user.
According to Apple's documentation on multitasking and execution in the background, the following types of apps are supported, but have to be explicitly declared:
Apps that play audible content to the user while in the background, such as a music player app
Apps that record audio content while in the background.
Apps that keep users informed of their location at all times, such as a navigation app
Apps that support Voice over Internet Protocol (VoIP)
Apps that need to download and process new content regularly
Apps that receive regular updates from external accessories
Your case falls under Apps that play audible content to the user while in the background, such as a music player app. You can find more information from the link provided above.
My goal: play MP3/AAC files from a web server (streamed, rather than downloaded in advance) in PERFECT sync between multiple iOS devices.
Two questions:
1 - Can AVPlayer stream existing MP3/AAC files, while continuing on to the next tracks in the background? Meaning, assuming the phone is locked, or another app is in the foreground, if I am playing a list of multiple MP3/AAC files, and one finishes playback, will the next track begin playing seamlessly?
2 - Can the new setRate:time:atHostTime: method in iOS6 AVPlayer allow for synchronized playback between MULTIPLE iOS devices? Meaning, I want to play audio in perfect sync between multiple iOS devices. I read the documentation here, but it's a bit confusing and I can't find any sample code to see how it works:
Matt's AudioStreamer is the best option for you , Avplayer and AVaudioplayer downloads the remote mp3 url synchronously before playing which takes time .
click here
For example, if I start a song in Pandora and then open Safari to browse the web the Pandora song will keep playing. However, if I start a song in Pandora and then open my app it kills the Pandora song. How do I let Pandora keep playing while my app is running?
You need to tell the iOS system what behavior it should use to integrate the two audio sessions. By default it cancels the background audio when you use audio. But this behavior can be modified as described in the AVAudioSession docs here.
To quote:
Working with Music Players
To play audio from a user’s iPod library along with your own sounds
(as described in iPod Library Access Programming Guide), you must use
a so-called mixable category configuration for your audio session.
There are two, alternative ways to configure an audio session as
mixable:
Use the AVAudioSessionCategoryAmbient (or the equivalent
kAudioSessionCategory_AmbientSound) category—which is always mixable.
Use the mixable category override property
kAudioSessionProperty_OverrideCategoryMixWithOthers, as described in
“Fine-Tuning the Category,” to make an otherwise nonmixable playback
category mixable. Having used one of these options, your sounds will
not interrupt a music player—and neither will a music player’s sounds
interrupt yours.
There are two reasons why your app might "kill" the background app:
It starts to play music of its own
You use too much memory for it to keep playing and the OS closes the background app
There is no special option you need to select; you just need to be a "good citizen."
I'd like to record what the iPhone is currently outputting. So I'm thinking about recording audio from Apps like Music (iPod), Skype, any Radio Streaming App, Phone, Instacast... I don't want to record my own audio or the mic input.
Is there an official way to do this? How do I do it? It seems like AVAudioRecorder does not allow this, can somebody confirm?
Officially you can't. The audio stream belongs to the app playing it ,and iOS.
The Sandbox paradigm means that a resource owned by your App can't be used by another App. Resource here means Audio/Video stream or file. Exceptions are when a mediator like Document interaction controller are used.
If you want to do this you'd have to start with deducing AVFoundation's private methods and find out if theres a way there. Needless to say this it wouldn't be saleable on the App store and will probably only be possible on a jailbreak.
Good Luck.
TLDR;
This is only feasible only from time to time, as it's a time expensive process.
You can record the screen while listening your songs on Spotify, Music or whatever music application.
This will generate a video on your Photos application. That video can be converted on MP3 from your computer.
Actually, this is not true. The screen recordings will not actually have the audio from Apple Music at all, as it blocks it. Discord also uses this pipe as well, so you cannot record Discord audio either this way.
I want to build a mobile app that has the ability to receive an audio file and then play said audio at a time previously set by the user. Does anybody know if it is possible on the iPhone to build such a function or is there no way around the user having to run the app and accept the audio file manually?.
For your own use, you might be able to build a VOIP and streaming audio app that would run in the background while maintaining a network connection and continually playing silence (until it got the file and/or it was time to mix audio with the silence). However, it is unlikely that such an app would comply with all SDK/App store rules.