Satnav and multitasking
in [UK Mac]
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From: zoara on 8 Jul 2010 15:54 How do the Satnavs work in iOS4 with multitasking? If you forget and leave one running in the background, does it quickly drain the battery to nothing, or dies it do something clever to avoid this? -z- -- email: nettid1 at fastmail dot fm
From: Jochem Huhmann on 8 Jul 2010 16:04 zoara <me18(a)privacy.net> writes: > How do the Satnavs work in iOS4 with multitasking? If you forget and > leave one running in the background, does it quickly drain the battery > to nothing, or dies it do something clever to avoid this? Apps can peruse a service in the background to continue to get a GPS fix regularly. They can't get maps etc. then though, which should lighten the load on the battery (by avoiding further CPU and heavy network usage). In how far these apps are clever enough to limit their battery load by falling back to use WiFi-triangulation or even using the gyroscope on the iPhone 4: I have no idea. It's not so that the full apps continue to run in the background, though. Jochem -- "A designer knows he has arrived at perfection not when there is no longer anything to add, but when there is no longer anything to take away." - Antoine de Saint-Exupery
From: Jon B on 9 Jul 2010 05:30 zoara <me18(a)privacy.net> wrote: > How do the Satnavs work in iOS4 with multitasking? If you forget and > leave one running in the background, does it quickly drain the battery > to nothing, or dies it do something clever to avoid this? > Co-pilot have said when it's been stationary for 10mins they turn off the GPS, but of course this doesn't allow for the times you get out of the car with it and then walk for 5hrs, at which point the phone would be dead. <http://blog.copilotlive.net/?p=1591> Think a key issue here is with multitasking you've got to watch what apps you're exiting sometimes... -- Jon B Above email address IS valid. <http://www.bramley-computers.co.uk/> Apple Laptop Repairs.
From: zoara on 9 Jul 2010 07:38 Jochem Huhmann <joh(a)gmx.net> wrote: > zoara <me18(a)privacy.net> writes: > >> How do the Satnavs work in iOS4 with multitasking? If you forget and >> leave one running in the background, does it quickly drain the > > battery >> to nothing, or dies it do something clever to avoid this? > > Apps can peruse a service in the background to continue to get a GPS > fix > regularly. They can't get maps etc. then though, which should lighten > the load on the battery (by avoiding further CPU and heavy network > usage). In how far these apps are clever enough to limit their battery > load by falling back to use WiFi-triangulation or even using the > gyroscope on the iPhone 4: I have no idea. It's not so that the full > apps continue to run in the background, though. Satnav apps keep an accurate GPS location (to allow them to continue turn-by-turn voice announcements). I doubt that wifi triangulation is even vaguely accurate enough; I doubt there's been enough development time to work gyroscope stuff into the apps. I'd be surprised if they do much more than simply use Apple's "continuous GPS" APIs. As the "real" GPS uses a lot of battery (as anyone trying in-car GPS without a cradle will notice), I'm wondering what happens if you forget it is running and leave it in the background when you get to the destination (for example). When I raised this as a question after multitasking was announced, it was suggested that a) GPS requests continue in the background, meaning that according to Jobs they have failed at multitasking, as this implicitly requires a task manager to kill the sat nav app b) it is somehow managed by Apple at the API level, eg continuous GPS only works for ten minutes while the requesting app is backgrounded, or it turns off if location doesn't change significantly for ten minutes, or [other]. c) Apple have entrusted the app developers to behave as good citizens and implement their own checks (similar to the above) which kill the continuous GPS in certain circumstances. I'm hoping b); c) is okay I guess, but difficult in practice to tell from b). But a) would be lousy. I have a nagging feeling it will be a)... -z- -- email: nettid1 at fastmail dot fm
From: zoara on 9 Jul 2010 11:52
Jon B <black.hole(a)jonbradbury.com> wrote: > zoara <me18(a)privacy.net> wrote: > >> How do the Satnavs work in iOS4 with multitasking? If you forget and >> leave one running in the background, does it quickly drain the > > battery >> to nothing, or dies it do something clever to avoid this? >> > Co-pilot have said when it's been stationary for 10mins they turn off > the GPS, but of course this doesn't allow for the times you get out of > the car with it and then walk for 5hrs, at which point the phone would > be dead. > <http://blog.copilotlive.net/?p=1591> Hmmm. That advice will work, but I'm surprised Jobs okayed it. The people who don't read the CoPilot blog are going to have troubles. I wonder how much this will add to support costs (and reputation) for CoPilot and for Apple? > Think a key issue here is with multitasking you've got to watch what > apps you're exiting sometimes... "If you see a task manager, you've failed at multitasking". -z- -- email: nettid1 at fastmail dot fm |