I'm looking for some way to let my app play a sound at a specific time while it's in the background (IOS4 multitasking). Currently, I use local notifications for that which works quite well, except for:
the sound will not be played if the phone is muted
the 30 second playback limit
I saw there's setKeepAliveTimeout:handler: but it's only available for voip-apps and since that's not the purpose of my app, I guess Apple would reject it because of this. I also saw a solution where an "empty" sound is being played until it's time has been reached, but - ignoring that this is not a very elegant way, anyways - I read that this, too, might get the app rejected.
Since there are a few alarm clock apps that do just what I'm looking for, I wonder how they implemented this functionality.
Thanks for any hints in advance!
If you seek a solution that will be approved by Apple, you're right you can't use the setKeepAliveTimeout:handler and even if you could - you can't set the timeout to something that's smaller than 600 seconds, so I guess it won't be of a great use anyway (besides that It's not guaranteed to fire the event even remotely close to the timeout you specified. For example, I set it to 600 seconds and some event fired as early as 360 seconds..).
About playing the silent sound, except the waste of battery, if you're app has legitimate use for background audio (if you're implementing an alarm clock, that's pretty obvious), I don't see a reason for your app to be rejected, as long as you don't try to use other background features (GPS signal, VoIP handlers, etc).
Here's one example app that used this "feature" for their benefit:
http://tapbots.com/blog/pastebot/pastebot-music-in-background
About other methods, you can look in this thread:
How do I start playing audio when in silent mode & locked in iOS 6?
On a personal note, it's not very easy to cope with background policies of Apple. Me and my company had (have?) a hard time just to maintain a simple VoIP connection due to all the limitations. My best advice is try to do as less as possible in the background as you can. If the UILocalNotificaion solution suits you, you'll probably should stick to it and live with the limitations.
Related
I already know how to keep play music at background in my app.
I don't want to know that.
I want this.
how to Automatically turn on ipot music in background & sleep mode at custom time.
it's thought impossible to me.
but that's possible. and no jail break.
i wanna know that. please help me.
Take a look at the following background task guide from the iOS docs
http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/BackgroundExecution/BackgroundExecution.html
There are restrictions on what can be carried out in the background. Certain apps that support audio, location, and voip are allowed to run in background using the UIBackgroundModes key. With the audio background task, it will not be suspended until the audio session stops.
It seems that you don't want to initiate a session until a certain time. You could potentially look at beginBackgroundTaskWithExpirationHandler: .
Also if you are looking for a timed alarm, you can always attach a different tone to a local notification.
As far as I am aware, there is no "out-of-the-box" way to do what your asking.
I'm thinking the answer to this is no, but does anyone know if a Bluetooth connection can be maintained in the background with iOS? I'm thinking I might be able to keep it around with the finite-task background API, but I haven't found anything indicating whether that's true or not. Another option would be to use GPS notifications and just reconnect every time the app gets a location changed notification.
You a right. It's a NO.
But if you use location change notification to wake up your app, you may have a short period of time to use Bluetooth.
I think that the Bluetooth connection should be maintained, but if your bluetooth application is not the foreground application it will not receive any data / commands, when it becomes foreground it will.
It is possible, I use this trick to allow an App to use foreground APIs for iBeacons to allow the app to range even when the App is in the background.
To range for iBeacons it uses a high power API and as so this is restricted to only run when the App is in the foreground and stops all delegates being called once the App enters the background.
By playing a silent audio file and adding the AirPlay capability to your plist it allows your app to run in the background just as it would if it was in the foreground.
I'm not sure if it will work for your case but as iBeacons do use the Core Bluetooth and Core Location frameworks it might just do what you are asking.
http://yifan.lu/2013/12/17/unlimited-backgrounding-on-ios/
Note although this trick has not been patched by Apple in iOS8 beta 5 it is possible they will in an update.
If you're using iBeacons, there are built-in APIs for handling when you enter/exit a beacon region, and you typically get ~5 seconds to range for beacons at that point before the app is put to sleep. Theoretically, you could start a background task w/ expiration handler that might allow you to range for ~30 seconds while backgrounded, but I have not verified this is the case. I do know that the background task can be started when normal CLRegions are entered/exited while in the background, and there is functionally no difference between CLRegions and CLBeaconRegions in terms of region monitoring, so if I had to guess I would say this is more-than-likely possible.
I need to develop an enterprise app that monitors the network traffic. Basically it detects if the user is in wi-fi or cellular data and save the amount of bytes was sent and received in a period of time.
I saw an App at the AppStore that do exactly this job.
Detecting wi-fi or cellular data is quite simple using the Reachability Sample provided by Apple.
My problem is to keep monitoring the bytes sent and received while the app is in background.
As it is an enterprise App, I used UIBackgroundModes "voip" to avoid the app to be terminated.
I also installed the setKeepAliveTimeout method and I'm able to see the logs each 10 minutes, BUT only for 10 seconds after the method runs. I mean, setKeepAliveTimeout brings my App to run a Timer for 10 seconds each 1o minutes.
I'm thinking wether or not a task in background is the best solution for my problem.
I'll appreciate any comments.
EDIT: Ok guys. Thats the perfect way to do it.
First of all you must read this:
http://www.christian-fries.de/blog/files/tag-ios.html
I tried this and it works really fine.
All we need to do is to create a second thread detached from the main one. This way we have a continuos threading running forever. You must see the GCD docs at Apple's website also.
Second thing you should consider for an enterprise App is to set it up as a voip App, this way iOS will put your App running even after a reboot. It's a special behavior iOS has to keep voip Apps running.
Thats it guys.
I hope it can help you.
We dont have access to this data. There is no way to measure traffic.
The app you saw made an estimation (eg. 1mb/min) and after applicationWillEnterForeground. then you calc time x estimated-traffic and there we go.
Unfortunately there is no way to measure,
so I did a traffic-reset in settings and then i streamed exactly 1 min music. after a few repetitions I had my results. The problem is, that this works only fine with static traffic-processes like audio or video.
hope could help
endo
EDIT: look answer below!
Background: Workout App is designed to have a continuous timeline that I can then input what exercise and reps I'm doing in real-time, then graph the results in real-time.
Issue: When the iphone sleeps for too long, we lose the continuity of the Timeline and it restarts. We haven't figured out how to keep the timeline updating while the App is sleeping. I've asked him to do a call to the Iphone internal clock and do the math on where the viewer should be and move them to that point on the timeline. However, he can't figure out how to do this.
Solutions: Have you folks heard of anyways to do this call to the internal clock? Perhaps a better question, can you think of another way around the problem in general?
You could try CACurrentMediaTime which returns mach_absolute_time in seconds. This should be accurate across sleep.
There is no certain way that can assure you app will be running in the background for ever. (If this is what you need)
Even Steve said is Multitasking, iPhone resources are very limited and this means that your app will might be killed while it is in the background without any kind of notification.
(Except by the notification you get when entering the background)
The best thing you can do is low your resource usage. (release as many objects as possible)
Because when the system needs memory it will start killing apps in the background starting by the app that uses more resources.
If you are implementing streaming protocols then is different.
Hope this helps
Ever since the first beta came out I’ve been trying to find out if “real” multitasking is possible — i.e. can you put a program in the background and have it hang on to a network connection indefinitely?
I’m thinking about IM or IRC apps, for example. I’ve compiled an app myself on iOS 4, and without changing a thing it appeared to stay running in the background, but for all I know it was just suspended to memory.
The docs say the best you can do is request up to 10 minutes, but in the developer presentation they showed off Skype sitting in the background and then notifying the user that a call was coming in. Does anyone know for sure how this all works?
It appears the answer is no. The API for Skype is a very special case, called the "voip" mode, and requires special behavior, such as marking the socket in use for VoIP.
You can receive alarm notifications in the background (such as time passed). The amount of time you are in the background running state is severely limited by the OS.
Android's background model is complete and in many ways much nicer.
Apple has a guide named "Supporting Multitasking In Your Applications" which you should be able to locate.
Apple's iOS 4 developer docs outline this all very clearly.
When your app is closed or switched away from, it is almost immediately "suspended", meaning the OS freezes the app's state. When the user switches back to your app, your code keeps running just where it kept off. You don't need to add any code to your app to do this, just compile it against OS 4.
The above is true in most cases. There are two reasons the "suspended" model may not apply:
1) If the device starts to run low on memory, the OS will start terminating suspended apps that haven't been switched to in a while, without warning. This is why it's in your best interest for your app to remember it's state as well, so if your app is terminated, then re-opened, the user doesn't really notice because it still returns to right where they left off.
2) Your app uses one of the "background" APIs. These are for audio playback, VoIP services, or location services. In this case, your app is allowed to continue running in the background but only has access to those APIs. Additionally, your app can designate certain long-running tasks as "background tasks" that need to be completed before the app is suspended or terminated, like uploading pictures to Flickr or rendering a video, etc.
The "background task" method doesn't cover pinging servers indefinitely, as there is a time limit for the task, after which it will be forcibly halted. Apps that need that sort of functionality are expected to implement push notifications, just as before.
That should clear this up. All in all I think it's a pretty elegant solution to multitasking on a mobile device.
iOS 4 applications can either be running or suspended. The operating system will try to keep as many requested applications as possible in memory, while all other applications are suspended.
Applications that run in the background can access features such as navigation, audio, and VOIP (but NOT instant messaging). So it looks like you might be out of luck.
-- PC World Multitasking on Apples iPhone 4
It is possible for apps to request background time. Read the docs. I would say it iOS is "controlled multitasking".
You can create a long running background task, I believe these can include networking features. Just have to set the background task flag on the work block.
https://developer.apple.com/iphone/library/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html
the OS can limit exactly how much time you get though... it will tell you when your time is up giving you a chance to cleanup nicely.
iOS 4 has "real" multitasking to some extend. There are two things to consider:
The UI event loop is single tasking. So only the front app executes on the UI event loop. Not a big deal: detach your main code form the UI event loop (maybe you need to redesign your app).
The OS "may" terminate your app if some criteria are met (e.g. low memory).
Currently one of these criteria is that execution time is limited to 10 minutes (real time not cpu time). However I expect this to change and see better criteria for background app termination (I hope to).
Apart from this you can have timers (event loops) in background.
There is no real multitasking in iOS 4.2 even. because apps will only be allowed to finish the task related to states..for small interval of time and then it will be in suspended state.. If you will set background task for long interval of time then... it will behave unexpectedly like no method will be called when you will try to run the app from anywhere..
You may be interested in this blog post that outlines how "multitasking" works in systems such as iPhone OS 4 and Android.
in fact u can do this, although it's not allowed by Apple. u gotta set up a toolchain in ur mac and use some unofficial SDK...
check http://code.google.com/p/iphone-backgrounder/ for more information
You should use the Push Notifications framework for the feature set you are creating!