I've seen claims on the net that the newly released iOS 7.1's iBeacon support.
Specifically:
The system is supposed to still notify your app about
didEnterRegion/didExitRegion events, even if the user explicitly
kills your app.
didEnterRegion/didExitRegion notifications are
supposed to be faster from the background and/or with the device
locked.
I have not been able to confirm either of these claims with my own testing. In fact, I seem to be less likely to get didEnterRegion/didExitRegion notifications from a locked device. (more accurately I seem to get didEnterRegion notices, but not didExitRegion notices). That could be because Apple made me remove my BLE background mode entries in my info.plist - I'm not completely sure. I'm still trying to sort this out.
I had trouble setting up my tests at first, but I have witnessed background region entry callbacks after killing an app in iOS 7.1 on both iPhone 4s and iPhone 5s models. See comments below for testing details and instructions to reproduce.
I have also done tests on background detection times on an iPhone 4S, and I still see delays of 15 minutes on iOS 7.1. My full test results and methodology are described here.
Finally, I have also done some tests on the fluctuations on the "accuracy" (distance in meters) measurement on the same device before and after the upgrade to iOS 7.1. I do not see an obvious difference in the noise on the estimate. The graphs below show results before and after the upgrade, with an iBeacon 0.5 meters away for 60 seconds then moved to 3 meters away for 60 seconds. In both cases, the transmitter was a properly calibrated iPhone 4S w/ iOS 7.1 and the receiver was an iPhone 5S.
iOS 7.0.6 Estimated distance
iOS 7.1 Estimated distance
As has been mentioned in several articles circulating around the internet, beacon sensing is available even when you swipe your app away from the multi-tasking view. However in my experiments, a region enter/exit event doesn't call the didDetermineState: directly (Probably because I hadn't been using the AppDelegate to initiate any beacon sensing but instead triggering monitoring based on UI events). Instead if you have registered for Background Location Updates, your AppDelegate's didFinishLaunchingWithOptions: method would get called with the value for key UIApplicationLaunchOptionsLocationKey in the parameter launchOptions set.
You can do a simple check like this to test if this is indeed a location update that has bought your app into the background to perform some task.
if ([launchOptions objectForKey:UIApplicationLaunchOptionsLocationKey])
You can then either register your monitored regions again or start ranging immediately.
P.S. CLLocationManager retains your previously monitoredRegions on app restore but without starting monitoring again using the same UUID and identity, you would not get the enter/exit region event in CLLocationManagerDelegate (which had brought your back up to life)
David has done some wonderful work on this, so I'm writing this cautiously... but I'm seeing something quite different from him in my tests.
I'm using two phones: an iPhone 4S running iOS 7.1 (11D167) and an iPhone 5S running iOS 7.0.6 (11B651). My iBeacons are manufactured and sold by Bluecats (www.bluecats.com), although I'm not yet using their SDK (ie. I'm just using CoreLocation) and I don't think the manufacturer makes much difference.
I'm getting response times of around 1-2 seconds on both devices when the app is running in the foreground and also when running in the background. The only difference is when I remove the app from the app switcher: iOS 7.0.6 never responds (or perhaps will do in 15 minutes), but iOS 7.1 responds in roughly the same time. When I say "respond", I mean that the CLLocationManager's locationManager:didDetermineState:forRegion: delegate is called by iOS.
I'm testing by actually wandering around my office with phones in hand, so I'm physically moving in and out of range. Strangely (?), in my early testing, where I was sitting at my desk and simulating moving in and out of range by removing and reinserting batteries, I was seeing much slower response times. Perhaps this is part of the difference?
In my testing I have seen the presence of a beacon go un-noticed by an app for up to 15 minutes, but I found something that's interesting. I'm using RedBearLabs mini BTLE sensors as ibeacons and their app to program the beacons, http://redbearlab.com/ibeacon/ (http://redbearlab.com/s/MiniBeacon_v1.zip), seems to have an something in it that immediately starts a scan / update of beacons. If I start a beacon up, and in my app it goes unnoticed, by starting then quitting the MiniBeacon app my app immediately notifies me that there are new beacons. This is the same result when entering or exiting. Their app uses CBCentralManager, which my app doesn't, so maybe a mixture between CBCentralManager and CLBeaconRegion is the way to go? I imagine CLBeaconRegion starts / restarts the bluetooth radio, so maybe that is the reason for this. Just taking a stab at it in hopes that someone with a more complete understanding can help resolve this.
Thanks
My testing also reproduces 15 mins to start scanning when my app is in background mode on iOS7.1.1. Just a bit curious, I have seen quite many youtube videos from different companies showing the app has been waken from background mode as soon as they approach their beacons. Is it sales trick?
Related
I am developing an app in Xamarin Forms which will show thing live position of the user on a map and all the users having the app can track other users movement.
Right now the app is working fine in android. But in the iOS foreground, android background it stops after some time. It is not at all running in ios background when I put the app in the background it stops showing the location and stops fully.
Please share some idea to keep the app live in background and foreground mode for the whole day.
Generally speaking, mobile OSs will stop your apps, when they are in the background for some time. How strict the OSs are depends on the OS and the version. iOS has "always" been very strict about it, Android has been a bit more loose in older versions, but is quite restrictive in newer versions. Anyway, getting the location in background is quite a common use case and OSs are providing you options to do it nevertheless, if you ask them politely.
iOS
As of iOS 11, there is a distinction between updating the location when in use and when in background. The user can choose which one to grant and you'll have to handle it appropriately.
According to this guide you'll have to add the NSLocationAlways key to your Info.plist to contimue getting the location when in background.
Android
From the Android developer guide
In an effort to reduce power consumption, Android 8.0 (API level 26) limits how frequently background apps can retrieve the user's current location. Apps can receive location updates only a few times each hour.
Anyway
The system distinguishes between foreground and background apps.
An app is considered to be in the foreground if any of the following is true:
It has a visible activity, whether the activity is started or paused.
It has a foreground service.
...
According to this, you can create a foreground service, see here more about it
For this reason, foreground services must show a status bar notification with a priority of PRIORITY_LOW or higher, which helps ensure that the user is aware of what your app is doing.
So if you are starting a foreground service that is shown in notification bar, you should be able to retrieve updates, even if your apps main Activity is not in foreground.
I have a graphics application that occasionally displays incorrectly after a sleep / wake cycle.
I'm wondering if there is something I should do on the Sleep or Wake events. I'm capturing these events already, because I hide the cursor in the app, and when the app wakes the cursor appears and has to be re-hidden. I'm creating my images with [[NSBitmapImageRep alloc ]initWithBitmapDataPlanes:outplanes, doing lots of bit manipulation on multiple images. I display the image full screen. Xcode 7.1, OSX 10.10
The error I get is a shimmering on the display as if my merge routines are using the wrong data.
I was assuming the sleep took a snapshot of all my data, including whatever is on the stack? It's hard to reproduce the problem, but my App is going to be running every day in a public space and uses the scheduler to sleep each night and autowake in the morning.
Should I reinitialise all my variables on a wake?
I can't see anything on the apple docs about actions you should take on these events.
It should not be necessary to worry about this. If it is, that is likely to be either a bug in your app, or a bug in Apple's code. Indeed, the cursor issue you mention sounds like a bug to me, and you should log a bug in Apple's bug reporter about that. Sleep/wake should be entirely transparent for apps that don't have a specific reason to care. You will need to try to pin down the issue you are seeing, somehow, and diagnose it.
I have made an app with live tile for windows phone 8. The tile is programmed to refresh every 30 seconds. When the run the app in the emulator or when I deploy the app in my cell (Lumia 920) the tile works fine. But surprisingly when I downloaded the same app from the market and run it on the same device the tile doesn't update.
I did quite a bit of research on this problem and found that a similar problem is observed by many other people which can be found here.
Kindly tell me what is going wrong.
Extra Info : I have tried resizing the tile, pin and unpin the tile and hard reset. I have also tried changing the refresh period (initially the refresh period was 5 seconds). I have also checked that the background task is allowed for the app.
Thanks,
Apurva Pathak
Background agents have certain limitations, as listed below.
Background tasks can minimally be run every 30 minutes. There is a debug-only API to run them more regularly, but this is not available for released apps.
Some low power devices do not support background agents
Background tasks are limited by number on each device and can be enabled or disabled from application settings.
They do not work when power saver mode is activated.
As Mahantesh correctly pointed out your tiles work when you deploy the application because the ScheduledActionService.LaunchForTest() is allowed to run for a 60 seconds period for debugging and testing purposes ONLY.
Therefore this method cannot be called and it wont work with a time limit less than 30 minutes if the application is published to the market and users download it from there.
I am in the process of porting a Flash Player-based game over to the Desktop (OSX and Windows) via Adobe AIR (3.1). The porting to AIR itself has gone rather smoothly. The one wrinkle I've been dealt is that the game will be distributed over the Steam network. In order to interact with the Steam Client, I've had to write a native extension to expose the Steam SDK APIs to AS3. The native extension support has been implemented for both platforms, and I have the application launching and communicating with Steam as desired.
The area I've run into trouble is dealing with Steam's Overlay, which renders overtop of games when it is activated. Essentially, when a game is launched, the Steam Client suspends the process in order to hook its Overlay library up to either D3D or OpenGL. Initially, the Overlay failed to appear at all as the AIR application descriptor had the default rendermode set to "auto." However, once I switched the rendermode to "gpu" the Overlay would appear as desired.
On the OSX side of things, everything works as expected. I can toggle in and out of the Overlay just fine. On the windows end of the spectrum, I've hit a bit of a problem when I activate the Overlay. Specifically, when the Overlay is enabled (it's rendering overtop of the game) and I either move the mouse or generate keyboard input, both the Overlay and the game both "freeze" (rendering stops) for 2-3 seconds. Additionally, I have noticed that when I open the Task Manager with the game running, the cpu usage is roughly 75-80%. The cpu usage remains the same when I first active the Overlay (which is desired). However, when I move the mouse cursor or press a key on the keyboard, the cpu usage drops to roughly 1%. This problem has occurred on 4 of 5 windows machines (2 XP, 3 Win 7) we've tested on. Naturally, I first contacted Valve about the issue since this only occurs when the Overlay is enabled. I've uploaded both the OSX and Windows builds for their devs to debug; however, my contact suggested I find out more about AIRs rendering/input as well.
Here is a snippet of a post with a Steam Dev detailing how the overlay works:
"The requirements for the overlay on Windows are as follows:
Game must use D3D7, D3D8, D3D9, D3D10, D3D11, or OpenGL
Game must call D3D Present() or OpenGL SwapBuffers() on a fast regular basis (these calls are hooked by the overlay and give it opportunity to do work). For instance 2D games that only call these functions when mouse movement occurs or graphics on screen actually change rather than every frame will not function well.
Game should use standard Win32 input messages, raw Win32 input messages, or DirectInput for input and the overlay will then detect hotkeys and hide/block input events from the game when active.
It sounds like your game may violate #2 and stops calling Present/SwapBuffers sometimes when the overlay is active. This may happen if you call these functions in response to user input which is now blocked due to the overlay being activated. You should guarantee you keep pumping frames and swapping at a regular interval even if input events aren't occurring."
After a little more prodding, the Valve devs profiled my application to determine if there was any specific problem occuring with the Game Overlay. Unfortunately, they were unable to find anything going on in the Overlay itself. This pretty much means that AIR on Windows doesn't like that the Overlay is blocking Win32 input messages. Here is the Valve dev's response:
"I got your depots and did some testing. Nothing unusual happens in the overlay. Profiling your app with xpref while the issue occurs and taking some minidumps to check callstacks it looks like the app just blocks up completely and uses zero CPU during the time it is blocked, when it happens it calls Present() only at roughly 1 second intervals until it recovers (maybe there is a 1 second timeout somewhere in the AIR code). It's hard to get much detail since I don't have any symbols for the AIR runtime libraries.
It does however look like this is somehow related to input state and AIR being unhappy with win32 input messages stopping. If I change our overlay to not block any input at all once activated (which obviously has some pretty big problems for usability, but just for testing purposes.) then the issue does not occur. It's possible that the AIR code has some weird logic where if it's seen some specific WM_WHATVER message it's expecting another right after and blocks on it waiting somehow.
Hopefully you can work out on your side or with Adobe as to why the application behaves badly in these situations and starts blocking and not presenting at regular intervals."
I've posted on the Adobe forums, but haven't had any such luck over there. Mainly, I'm hoping that someone has either dealt with this before or has an idea about how I could possibly get around the issue. Any suggestions, comments or thoughts would be greatly appreciated!
As it turns out, there is an bug deep in AIR core framework that is the root cause of this issue. Adobe has confirmed the bug, and they are working on a fix for the Cyril (AIR 3.3) release. The status of the bug (#3089755) can be viewed in the Adobe AIR bug list.
In the short-term, I was forced to detect Windows messages that were being consumed by the SteamOverlay, and pass on fake messages to prevent AIR from locking up. I accomplished this by using the Windows API SetWindowsHookEx along with the WH_DEBUG and WH_GETMESSAGE hooks. This is definitely not a desirable approach, but was needed in the short-term until Adobe releases a fix.
Is it possible to track the accelerometer value while under the lock screen?
I managed to write a simple application which counts from 1 up to 100 using a timer which fires an event on which I increment a counter.
But when I use register a handler for the ReadingChanged event of the accelerometer it will not be fired anymore once the screen has been locked. Even if I unlock the screen again I will have to readd my handler.
the msdn documentation tells on the one page:
http://msdn.microsoft.com/en-us/library/windowsphone/develop/ff941090(v=vs.105).aspx
"Valid reasons to disable idle detection in Windows Phone OS 7.1 applications include ones where core functionality continues while the phone is locked (for instance, an exercise tracking app)"
but the sensor api also tells:
http://msdn.microsoft.com/en-us/library/windowsphone/develop/hh202968(v=vs.105).aspx
"The Sensor APIs cannot be used while the application is running under the lock screen. For more information, see Idle Detection for Windows Phone. The Sensor APIs also cannot be used in background agents. For more information, see Background Agents Overview for Windows Phone"
I hope they will change the api soon, because of that it is not possible to write any good sleep tracking / sport tracking applications ... :(
I was helping a guy with this a couple of days ago. He had an app that tracks GPS and accelerometer data under lock screen.
Turned out the app accelerometer data stopped tracking when under manual or auto lock screen.
There may be an issue here to be looked into.
Under lock screen it is a good idea to minimise power usage... disable all uncessary code, like ui updates. My understanding of one the motivations for idle detection and running under lockscreen being opened up during CTP was in response to a lot of feedback from developers of map/tracking apps that basically need this for their app to be of any use.
I'm not sure of the usage case where you'd want to use the accelerometer under the lock screen.
Apps typically run under the lock screen when you need them to do something when you're not interacting with the device. e.g. playing music or downloading a large file.
If you wanted accelerometer data I'd assume that the device is being held and, therefore, presumably, looked at. Given this, why would you therefore want to run under the lock screen?
That being said, if you had a good reason to do so, you should still be aware that:
when your application runs under a locked screen, it ... must minimize
power usage
(from the Marketplace Certification Requirements.)
In my understanding, reading values from sensors is not minimizing power usage.