I can detect that the iPhone went to sleep and came back from sleep, by using the applicationWillResignActive and applicationDidBecomeActive. But how do I find out what kind of interrupt it was. I am making an audio player application, and need to keep the audio playing when the iPhone goes to sleep (which I know how to do). But I need to interrupt the audio when a message, alarm or low battery interrupt occurs. Also I need to resume the audio when the event is over.
So how do I differentiate between these different interrupts.
That information is probably not available to your app, but here's some things to try.
In applicationWillResignActive:, check the NSNotification's object and userInfo properties to see if there are any hints there.
Register to receive all notifications posted to the default notification center:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(didReceiveNotification:) name:nil object:nil];
Your method will be called when anything is posted. Log the notification object and userInfo dictionary and maybe you will see a useful notification being posted. If you find one, you can register just for that.
This is the most hacky, but you might be able to get access to the alert that is displayed if it is a message or battery warning. Alerts are displayed in a UIWindow over your app's main UIWindow. You could register for UIWindowDidBecomeVisibleNotification, then look at the window's subviews to see if you can find an alert or some other useful clue.
All of the above methods would be relying on undocumented behavior to work, and could possibly get your submission rejected from the App Store. None of them involve private method calls, though you could argue that observing an undocumented notification name counts as private API. In the end, Apple's opinion is the only one that will matter.
Personally, I'd try it, making sure the code fails gracefully if and when the system changes.
Use an audio session?
Related
I am working on a mobile game, which appearantly crashes when the Low Battery alert is displayed. It works fine on low memory, incoming calls and other messages.
Its a pain to test and debug this, since I can find no terminal or iPhone simulator way of simulating this situation, so I have to charge my phone up a little bit, launch the app, wait for it to drain its power, and start all over again.
Does anyone know of a way to produce this error in a realistic way? Hopefully something that isn't too stressful on my iPhone battery.
Unfortunately, there is no good way to simulate a low-battery environment. You actually will most likely need to physically charge your device's battery until it is just above the "low battery" state and then debug your application.
To address what others have said:
There is no way to simulate low battery notifications. The project
that #Bo. provided does nothing more than schedule random
UILocalNotifications. It isn't all that much different than just
showing a UIAlertView in your app.
You could try what #Andrew R.
said and use the private methods found in the UIDevice header.
But it is doubtful that you will exactly mimic the effects of a real
low-battery environment.
Although it is a pain to have to wait for you device to actually hit the low-battery state, you could add some battery-draining code to your app to assist you. For example, using the GPS might drain the battery a bit quicker.
Good luck.
Did you try simulating the low battery notifications? There seems to be a project that does that: https://github.com/MegaEduX/LowBattery
Assuming this is for testing purposes only, you could give the following private UIDevice methods a try:
-(void)_setBatteryState:(int)state;
-(void)_setBatteryLevel:(float)level;
You'll have to experiment to see what parameters they expect, or whether they have an impact at all.
In iOS there is way to simulate "Low Battery"
Battery monitoring is enabled by setting to YES a property of the UIDevice singleton:
UIDevice *device = [UIDevice currentDevice];
device.batteryMonitoringEnabled = YES;
iOS provides two type of battery monitoring events, one for when the state changes (e.g., charging, unplugged, full charged) and one that updates when the battery’s charge level changes. As was the case with proximity monitoring, you register callbacks to receive notifications:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(batteryChanged:) name:#"UIDeviceBatteryLevelDidChangeNotification" object:device];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(batteryChanged:) name:#"UIDeviceBatteryStateDidChangeNotification" object:device];
I have an app, that will keep track of everything the user do in the iPod app. To do this, I added few observers to NSNotificationCenter, like MPMusicPlayerControllerNowPlayingItemDidChangeNotification. But my problem is, I only get those notifications when my app is in the foreground, if its in the background, the system add the notification to a queue, and then the next time my app becomes active it delivers it to me. I have no interest in this queue, since I want to receive real-time notifications.
Is there any way for me to get those notifications even if my app is in suspended state? I want to run just 3 lines of code everytime I get this NowPlayingItemDidChange notifications for example.
Here is where I add the observer.
MPMusicPlayerController *iPodMediaPlayer = [MPMusicPlayerController iPodMusicPlayer];
NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
[notificationCenter addObserver: self selector: #selector(handle_NowPlayingItemChanged:) name:MPMusicPlayerControllerNowPlayingItemDidChangeNotification
object:iPodMediaPlayer];
[iPodMediaPlayer beginGeneratingPlaybackNotifications];
Also, if I add another kind of object to the observer instead of iPodMediaPlayer, the observer won't call the method.
Thanks a lot,
Abras
iOS applications are suspended when they are not in the foreground. There are three exceptions to this rule. You can have code execute in the background if your application is
a) Playing audio. This means the application itself is actually generating audio. My understanding is that the MPMediaPlayerController iPodMusicPlayer object only controls the playback of the external iPod process, rather than playing audio from the app itself. Perhaps you could have some success if you called applicationMusicPlayer instead of iPodMusicPlayer and set the appropriate background flags in your applications Info.plist. This seems like the most legitimate way to get your application to work, but you wouldn't be able to control iPod playback from the iPod app, only your app and the system audio controls.
b) Get your app to monitor the location. If the app is using the GPS it can continue to execute in the background. Downside to this is that the GPS will drain battery, and users might be creeped out that you're requesting their location.
c) Ask UIApplication for extra time. If you use UIApplication's beginBackgroundTask method, your application will continue to run for a finite amount of time in the background. If your users are going to come into your application once every ten minutes or so, this could work as well.
Hope that helps.
Multitasking in iOS is currently a very restricted one. You may start a background task using beginBackgroundTaskWithExpirationHandler: method (of an UIApplication object), but it is intended to finish a finite-length task before going suspended. All background tasks may expire (and get terminated) before it finishes its job. You can check how much longer your application can run by checking backgroundTimeRemaining property of the application object.
As I explained here iOS receive Media Player Notifications when app is in background, there seems no way to get notifications from iPodMusicPlayer.
About Omar Raul Qazi answer:
a) i tried and I had no success. The music kept going down when pressing home button. I think this background flag only works for normal AudioSessions and not for MPMusicPlayer...
b) I am not sure this would work and I don't think Apple would like it when looking for approval
c) You can run in background only synchronous task. You cannot wait there for a notification. Am I wrong?
I have a UIWebview within a UIScrollView. Within the webview I have an embedded YouTube movie. When I play the YouTube movie everything works fine, however, when I press the fullscreen button the movie starts playing behind the webview. Bringing the WebView to the front does not work, because I want the scrolling capabilities of the ScrollView to do horizontal scrolling.
Basically, you want to be able to detect when a movie starts playing fullscreen and arrange your views appropriately. Then, when the fullscreen playback ends you want to be able to get your views back to how they are.
The problem is there's no documented way to hook into or detect when a UIWebView triggers video playback in full screen.
I said 'documented way', because there are some notifications you can use to detect when a UIWebView triggers fullscreen playback. You can just listen out for them and rearrange your views accordingly. However, I don't necessarily recommend this, because they're undocumented and subject to change (in fact, they have a spelling mistake in them up until iOS 4.3, see answers below).
// For iOS 4.3 and above:
UIMoviePlayerControllerDidEnterFullscreenNotification
UIMoviePlayerControllerDidExitFullscreenNotification
// For iOS 4.2 and below:
UIMoviePlayerControllerDidEnterFullcreenNotification
UIMoviePlayerControllerDidExitFullcreenNotification // (note spelling mistake)
Finding these out was a bit of a pain - there are actually several more notifications that get triggered when a YouTube video in a UIWebView gets played back. To find them out you'll need to drop a breakpoint on all posting of notifications, and then manually inspect the memory locations of those notifications to figure out their string names. I don't actually think anyone has pulled these out before, because when I google them I get nothing. But they do work, promise!
I hope being able to get notified when the fullscreen playback is entered/exited will be helpful, with the massive caveat that Apple could change this undocumented behavior at any time. Your app won't get rejected outright for using them (because you're not calling any undocumented methods), and I've used it in shipping apps. But it's still not the best idea in the world...may be the only option you have though.
Edit: To clarify, based off the comment below: they're not constants, so you'd need to put them in quotes if you were registered for notifications.
For iOS 4.3+, Apple have changed the names of these notifications:
UIMoviePlayerControllerDidEnterFullcreenNotification now is UIMoviePlayerControllerDidEnterFullscreenNotification
UIMoviePlayerControllerDidExitFullcreenNotification now is UIMoviePlayerControllerDidExitFullscreenNotification
Please pay attention: The term "Fullcreen" has changed to "Fullscreen".
Thanks!
Just wanted to confirm that this works after playing around with it for awhile. You can get direct access to the view that the video is playing in. This is a blocks method of registering for the notification and pulling out the pertinent views.
Notice: You will need to delay adding subviews and/or access Apple internal subviews to remove the navbar for further customization.
[[NSNotificationCenter defaultCenter]
addObserverForName:#"UIMoviePlayerControllerDidEnterFullcreenNotification"
object:nil
queue:nil
usingBlock:^(NSNotification *note){
MPMoviePlayerController *theMovieController = [note object];
UIView *theDestinationVideoView = [[note userInfo]
objectForKey:#"UIMoviePlayerControllerFullscreenViewUserInfoKey"];
}];
I want a functionality in which i want to detect if my device is being shaked.The problem is i can detect the shake with didAccelerate method of UIAcceleratorDelegate , but i dont know how to detect if the device is still shaking. I want to play an audio file when the user shakes the device for first time,i have to check if the user is still shaking the device while playing the 1st audio file,if it is still being shaked, then i have to play another file.
See the sample project GLPaint from Apple which was found by visiting http://developer.apple.com/iphone and entering "shake" in the search box. Developer account not required.
You might consider writing a Method that runs in a separate thread that polls wether your device is being shaken every now and then and fire events that you handle somewhere else in your code (or instead of that, handle whatever you want to handle within the threads context itself, even tough i would not recommend doing that).
You just have to make sure, that your "shake-detektor"-thread exits at some point in time, you probably want to do that when the second audio file stopped playing. So your loop could test on that condition.
Hope I could help a bit.
I'm using the SoundEngine provided with Apple's crash landing example.
After an interruption such as an incoming phone call or an alarm I call to applicationWillResignActive: inside my delegate, in order to pause the game and save the state of it. After the interruption ends I return to my game but the sound is gone. Even if i reinitialize it with SoundEngine_Initialize() the game still wont reproduce any of the sounds, unless i restart my app.
How can I restore my game sounds after the interruption ?
Have you looked at the sound manager class used by 71squared ? You can likely just use their sound manager as is... but if you wanted to role your own, you can look at thier code as I know they have solved this in their code.
http://www.71squared.com/2010/01/latest-sound-manager-class/