I want to build an Ionic app that can still use accelerometer data while the app is minimized (runs in the background).
I have tried using:
The Ionic Device Motion Plugin
https://ionicframework.com/docs/native/device-motion
The Device Motion Web API that is supported by browsers https://developer.mozilla.org/en-US/docs/Web/API/DeviceMotionEvent
The Generic Sensor API that is documented to be supported by Chrome browser https://developers.google.com/web/updates/2017/09/sensors-for-the-web
The first two work in the foreground but won't work while the app is in the background (the accelerometer readings are paused and are resumed while on the foreground again). The Generic Sensor API won't work at all, even if I use this polyfill: https://github.com/kenchris/sensor-polyfills
I have also tried the Ionic Background Mode plugin, however, the accelerometer reading are still being paused in background.
https://ionicframework.com/docs/native/background-mode
How can an Ionic app use the accelerometer while in background? Any plugin that I am not aware of its existence (e.g., the Ionic Background Geolocation lets the app receive locations while in background)? Any other way?
Related
I am working on a medical related app where a medical device interfaces via bluetooth with an iphone. However I cannot figure out how to allow the app to run indefinately in the background. Right now it only communicates when the app is open. I have been reading a lot of questions related to this and I haven't managed to find an answer which fits. I'm sorry if this is a duplicate. Can someone point me in the direction of how to implement this.
ETA - I just got confirmation that this is supposed to be able to go on the App Store.
Did you come across this question: Background time issue for Bluetooth LE app for Iphone 4s
It seems that adding the background mode bluetooth-central (see documentation) can enable your app to run in the background while handling bluetooth events. As noted in the question above though, you could always set background mode to audio and play a blank looping audio track to keep your app alive and responding if you don't need to be on the App Store.
I am using CoreLocation to determine user's location to calculate the distance and show the route on the map. To minimize battery usage I am turning off GPS after getting location and turning it on again after 1 minute. When the application is active everything works fine, but after sending it to background and turning off GPS, the app seems to be inactive at all, it doesn't output anything (using NSLog()). I have added directive to info.plist file to allow the application to run in background. When I don't turn off the GPS in background the app works as well as in foreground.
So my question is the following: does GPS always need to be turned on in background to prevent the application to be suspended or there is another workaround (because the turned GPS drains the battery)?
P.S. I am new to iOS and mobile development at all, so maybe there are some tips that I have to know.
See http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html
Apple does not support long running background task in general.
This does only work for specific tasks:
audio,
location,
voip,
newsstand-content,
external-accessory,
bluetooth-central and
bluetooth-peripheral
When you do not use any of that, your app could be suspended.
In your case ypu have specified location, but disabled the location update. Then for apple there is no reason to keep your app in background mode.
I'd like to build a pedometer which runs in the background on iOS5 devices. I understand the Core Motion framework can be used to accomplish this, like Nike+ is doing with their pedometer app.
I've also heard that there are restrictions on when Core Motion can be used in the background, specifically the OReilly's iOS 5 book says, "In iOS5 Core Motion is legal while your app is running in the background. To take advantage of this your app would need to be running in the background for some other reason."
This seems strange to me. Does this mean I have to have an "excuse" to use Core Motion in the background?
Yes, in order to run your app in the background, your app has to be in one of a few blessed categories: music, location, VOIP.
EDIT:
You can find the docs here: https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/CoreData/Articles/cdRelationships.html
Just make it location aware. Log the pedometer activity and the GPS location.
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.
For the sake of this question, assume I plan to build a Google Latitude client app for iOS 4.
my app needs to upload the user gps location every two minutes, and also download the user friends locations. - in the background!
my app can't wait to be woken up by the OS on cellular tower switches (because they may only happen after 2 KM, while my app needs constant gps updating), so I understand I can create a thread, similar to the ones GPS navigators use, to run in the background.
I have no knowledge in iPhone programming, I just need to know if my app is feasible.
Will I be able to access the internet from within the background thread (and upload the user gps location), or is it restricted to only sampling the GPS location.
1.
Will Apple approve such an application, or is this type of use forbidden? because my app isn't realy critical such as a gps navigator
Thanks!
As Don said, iOS will send location events to apps that support it. From there, the app can do what it needs to do with the location event.
Background apps can register for one of three options:
Significant changes only: a low-power way to track location that only wakes the app up when there's a "significant" change in location
Standard location services: compatible with all iOS devices that can use location services, allows you specify change in distance, and works in background. However, if the app has been terminated or suspended, iOS won't attempt to relaunch the app.
Continuous location services: allows the program to receive continuous location updates and iOS will not suspend the application when sent to the background.
More info: Executing Code in the Background and Location Awareness Programming Guide
If you take a look at Executing Code in the Background, Apple provides guidelines on what multitasking-aware apps should and shouldn't do.
You will receive the locationManager:didUpdateToLocation:fromLocation: message in your app. In there, you can do whatever you need to, although you should not update the UI or use Open GL if your are in the background.