Is it possible to use the external speaker volume controls of iphone as a control for an App you have developed?
For example as a control of a timer app for which the enable button for the timer to start counting is the top external volume button and disable timer is the lower external button.
If so, which classes of iOS 4 sdk can override those external buttons for an application or those external buttons are locked only for volume controls and nothing else?
I have seen a video of the Camera+ app that supposedly uses the volume key to snap a picture (instead of touching the button on the screen). http://taptaptap.com/blog/volumesnap/
I, myself, was pretty confused when I saw that and thought it must have been a mock up or something. But I asked around and apparently, if you're running an audio player, you get notifications when the volume keys are pressed.
The idea was put forward that if you can run a silent audio on a loop and hook into the volume key notifications to do what you want.
However, I've looked at both the AVAudioPlayer and the MPMoviePlayerController class documentation and can't see any such notifications. I suspect they're private, which isn't very useful.
Related
I'm working on a radio alarm clock, and i have some issues.
I am using local notifications for the alarms, so it has a gentle fallback if the app is not running.
I am well aware of the limitations of the device, and i know what i can and cannot do when the device has gone into background.
But my question is this:
I have seen other apps starting an audio streamer when i've locked the device. How is this possible? May this be inside an execution-timeframe?
How is the best way to implement this? Is it any way i can activate a streaming session when the device is locked?
Edit
To clarify: I know how i make audio play in the background. But the issue is triggering the audio-playback when an local notification or some other event fires.
One app that seems to do this, is Radio Alarm Clock. I haven't tried it for long period of times yet. But it seems to do this. A video demo of the app: http://www.youtube.com/watch?v=KJQiFOcdBWk
Have you already declared your background task?
Support for some types of background execution must be declared in advance by the app that uses them. An app declares support for a service using its Info.plist file. Add the UIBackgroundModes key to your Info.plist file and set its value to an array containing one or more of the following strings:
audio — The app plays audible content to the user while in the background. (This content includes streaming audio or video content using AirPlay.)
iOS App Programming Guide - Implementing Long Running Background Tasks
You can add this by clicking on your main project icon, then under the Info tab you can add "Required Background Modes" to the "Custom iOS Target Properties" section. "App Plays Audio" will be one of the three default values.
Big Edit With New Answer:
If everything else is already in order, you can keep your app running in the background using the UIApplication method
- (UIBackgroundTaskIdentifier)beginBackgroundTaskWithExpirationHandler:(void (^)(void))handler
detailed here: UIApplication Class Reference
with an example here: Hour 21: Building Background-Aware Applications
This allows you to run an instance of NSTimer which triggers your music player. The difference between this approach and UILocalNotifications is that this method never lets the app fully enter the background mode, the music player exists the entire time which subverts the need to create it from the background, which looks to be impossible.
There may be limitations to how long of a timer you can set, I haven't tested this past 14 minutes out.
we can easily capture a view(screenshot) programmatically in iPhone.
But i am trying to capture screen automatically after every 5 seconds.that also, can be done.
But my main objective is , to capture screen, even if the app is closed, i.e in background.
Apple doesn't allow to background process to run for a long time, but can we do it for 5-10 min in background.
Capturing screen,even if the app is closed.Ofcourse user can close this function, within the app.
Apple might reject this, but is this possible ?
Regards
This is possible but it's not easy. You can register you app (via a .plist setting) as being a media app, this will allow it to run in the background. This is normally to allow media apps to continue playing music when the app is sent to the background. However if you are careful you can get it to do other thing in there too.
In your plist under "Required Background Modes" add a key "Item 0" and set it to "App plays Audio". This will mean you can do it.
You will then have to using AVAudioPlayer, play a silent sound that is say 5mins long, and then register one of your controllers for the AVPlayerItemDidPlayToEndTimeNotification notification. Then when this calls back, you can have your bit of code that, first takes a screenshot, and then starts the sound again.
This is the general concept, look somewhere like :
http://mobile.tutsplus.com/tutorials/iphone/ios-sdk_background-audio/
for how to set up the audio playing.
Just a note: APPLE WILL REJECT THIS!
If you are making an app for personal use only, this is fine, but will never make it to the app store.
Hoep this sheds some light on your situation! :)
I am playing the sound in my App and sound still continue play even when App enter into background i want to control the Volume of that audio when it enter into background . Like in this APP example.I want audio volume remain maximum even user try to turn off the volume. I am unable to splve it can any one out there help me out.
if you are using AVAudioPlayer the just use AVAudioPlayer instance say player like this:
player.volume=1; //for maximum volume
This is AVAudioPlayer's volume, and in reply to your question that even if user minimizes volume of Iphone it should remain in full, then you should know that according to apple policies, there are things which have control for user only, this is what they call user privilege, your app can not control iphone volume,
and for controlling player volume (you don't need any effort if you talk about iphone volume) , i am little doubtful how you want to do this, i mean you must have some button or horizontal slider to achieve this, anyhow proceed with your logic with the delegate method
- (void)applicationDidEnterBackground:(UIApplication *)application
in your appdelegate class
I am writing an iPad app that uses the "Flite" text-to-speech engine to announce specific events. The Flite engine uses an AVAudioPlayer instance to play the speech audio once it renders. For fun, I decided to add some simple controls to my app to allow the user to control iPod playback (next, prev, play/pause and volume - the basics) while my app is running using MPMusicPlayerController (of course).
The problem I am having is that when I adjust the iPod volume using MPMusicPlayerController, all of my audio is affected, including other sound effects and the speech audio. I set the volume for these other audio players (AVAudioPlayer instances) to 1.0 before playing the sound but it seems that the volume is always capped at whatever the iPod player volume is set to...
Is this normal? And what can I do to get around it? I want my app's audio to play at system full volume regardless of the volume level of the iPod player. (Example: The user had set the system volume to 80% of the device's max. I want my app to play audio at 100% of that 80% while allowing the user to adjust the iPod audio playback to 0-100% of that 80%.) Note: I am not interested in "ducking" but setting the iPod volume lower at all times while my app is running (background music).
I also have the problem, that -sometimes- when you first launch the app and press play on the iPod player (which sends the [player play] call), the iPod does not respond. If I press the home button, go into the iPod app and start playback then, once returning to my app, it works fine. What the deal with that?
Thanks in advance for any help!!
It could be something to do with the audio session category you've specified. Check out the Audio Session Programming Guide to see if you've chosen the right category.
The volume buttons on the side control the system volume and by extension the volume of your app's sounds.
I guess it's considered to be the Master volume control.
you can set the volume for specific samples or sounds using the AVItem's setVolume
[item setVolume]
You can create an AVItem to reference an existing sound file in your application or on the iphone. The code is pretty simple and looks like this -->
AVItem *item [[AVItem alloc]
initWithPath:#"the file"];
[item setVolume];
btw, this will not affect the rest of the audio channel (instantiated by some kinda AVController object) and the volume that you've set in your code will not be displayed on you screen so im not sure if you can change it at run time.
I have a soundboard application that plays mp3 files using AVAudioPlayer. The sound can be adjusted to high while listening to any of the clips.
My problem is when the phone is in use and I navigate to the app to play the soundboard the volume is set very low. I'm trying to make it so the the sound from my app can be heard by the person on the other line. They can currently hear the sound but its very low and hard to make out. Is there a way to raise the volume in my app while the phone is in use?
Have you tried setting the AVAudioPlayer volume (playback gain) property to 1.0 (max)?
This could be something to do with the hardware volume settings, i.e. when you're in a call the rocker buttons on the side of the phone control the volume of the call. This volume may be controlling the volume of the app as well. May be worth increasing the volume of the call and see if this increases the volume of the app too. If so, then work for a solution to that problem such as implementing an MPVolumeView in the app and customising its behaviour.
If a phone call is answered, while your app is launched, your app is no longer running until the phone call terminates. At the end of the call you could adjust the AVAudioPlayer volume to 1.0 (100%).