I'm developing a map application for Android Wear with the possibility to log routes with the GPS. Since logging a route can go on for a while I would like to save as much battery as possible while logging but still, I need to show the current speed and distance to the user. My idea is to use the KeepScreenOn flag to stay in the current app and then lower the brightness of the screen to a minimum when logging.
The problem is I don't know if that's good enough for saving battery or if you guys have a better idea? Is it possible to have ambient mode for an app that is not a watch face?
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I'm exploring the end user experience for a beacon prototype but I'm struggling to find any end-user scenarios that involve the app becoming active / opening up on the screen when within range.
I can get the app to send a notification and this is the most likely experience on both Android and iOS but does anyone know if it is possible to get the app to open up?
It's unlikely that I'd want real customers to have their experience interfered with in this way, I think it's ok if the app is already running and is open but not if it's running but not open.
Thanks
On Android this is possible. The reference app for the Android Beacon Library demonstrates how to do exactly this.
On iOS, it is not possible due to OS security restrictions. See here for details. The best you can do is send a local notification to the user when the beacon is detected, then if the user gestures to it, bring up the app.
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?
I am developing a windows phone app that uses users current location, I am making the app in 7 OS. My question is, Can I track the location in background, that is when the screen is locked?
I know this is a possibility in wp8 as it provides us with GeoLocator class, but can I achieve this in wp7? I am basically making a runtracker app hence I would like my app to track the location even when its in background, is it really feasible?
Your help is always appreciated!!
It is possible to keep the app running under lock screen, as it does, for example, Endomondo app.
Using Idle Detection, you can keep the app on, although screen is locked, and you can keep on tracking the location. Actually, it is not running in background, but in the foreground. Just the screen is locked. So, be careful not to drain user's battery.
You have to set the PhoneApplicationService.ApplicationIdleDetectionMode property to Disabled, for example in InitializePhoneApplication() method in App.xaml.cs:
PhoneApplicationService.Current.ApplicationIdleDetectionMode = IdleDetectionMode.Disabled;
Note that there are special certification requirements for this type of apps. Refer to section 6.3 (Apps running under a locked screen) of the following page:
Additional requirements for specific app types for Windows Phone
I got the same problem in one on my apps..
I don't think it' s feasible for wp7..
Bt if you want to do it with wp8 you can refer following link.
http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj681691%28v=vs.105%29.aspx
And to know about background supported and unsupported API's http://msdn.microsoft.com/en-us/library/windowsphone/develop/hh202942%28v=vs.105%29.aspx/css
GeoCoordinateWatcher Class exists in WP7, but here is the documentation from MSDN -
This API, used for obtaining the geographic coordinates of the device,
is supported for use in background agents, but it uses a cached
location value instead of real-time data. The cached location value is
updated by the device every 15 minutes.
More Info : http://msdn.microsoft.com/en-us/library/windowsphone/develop/hh202962%28v=vs.105%29.aspx/css
I want to use accelerometer in my app when the user sleep. When WP7 is locked then accelerometer is turned off so I must set UserIdleDetectionMode to disable and then I disable lock screen but now the phone woudn´t be saving battery so what I must do for saving battery, for doing fake lock screen?
The other apps I've seen which do this recommend that the user plug their device in while using it.
I don't think this is an unreasonable solution as it's safe to assume that most users will charge their phones over night anyway. (Due to current battery technologies and the power consumption of the phones.)
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.