Comments on: Accessing the GPS in iPhone Safari

By: Billp

Billp — Fri, 27 Aug 2010 23:38:24 +0000

Thanks for the reply on timeout. I’m resigned to requiring my users to set auto lock to never and to reduce screen brightness.
I’ve got a live demo that stores path info running at logsitall.com/geo/geo-second.asp – feedback would be welcome.

By: Flemming

Flemming — Fri, 27 Aug 2010 06:39:24 +0000

@Bill P – I agree with CSS Ninja – unfortunately this cannot be done through the Javascript API. The only way to keep getting position updates in Safari via the JS API is to manually disable the sleep setting in the iphone.

If you are writing a native app, you can however work around this “problem” by doing something like this:

- (void)applicationDidFinishLaunching:(UIApplication *)application {

application.idleTimerDisabled = YES;
[window addSubview:[rootViewController view]];
[window makeKeyAndVisible];
}

But this API is not exposed via Javascript, so that can only be done in native apps. I wrote a hybdid app that almost had no native code other than the code above to disable the sleep timer – the rest of my application was written using the javascript API.

As CSS Ninja says when you disable the idleTimer it will lead to serious battery drain, because not only will the GPS keep updating, the screen will also be on maximum brightness, the accelerometer will keep updating etc. etc. It would be nice if I could just turn on GPS updates and let the rest of the hardware go into sleep as usual.

By: The Css Ninja

The Css Ninja — Thu, 26 Aug 2010 23:27:26 +0000

@Bill P – If you’re wanting the watchPosition function to keep updating the users location even when the phone is asleep I think you’re out of luck. Not only would that be a serious privacy issue but also a serious battery drain.

By: bill patton

bill patton — Thu, 26 Aug 2010 00:57:24 +0000

thanks to this (and some other) great tutorials i’ve got my web app running – however i’m curious about how to control the ‘time out’ value of the browser. Once the iPhone goes to sleep it stops sending position and location. Can this be controlled?

-bill

By: The Css Ninja

The Css Ninja — Thu, 19 Aug 2010 00:05:07 +0000

@cam – You could call the getCurrentPosition using the setInterval method and set it to fire every 5mins(300000ms) and then save the position using localStorage e.g.

navigator.geolocation.getCurrentPosition(success, fail);
 
function success(pos) {
    // Do something with position
 
    // Store position in localStrorage
    window.localStorage.setItem("coords", 
    [pos.coords.latitude,pos.coords.longitude]);
 
    var getPositionInterval = window.setInterval(
        "navigator.geolocation.getCurrentPosition(success, fail)",
         300000);
}

By: cam

cam — Wed, 18 Aug 2010 06:56:55 +0000

Would it be possible to write a small app that gets gps periodically. Lets say every 5 minutes and then writes a file to the iphone with the coordinates. Could this easily be done in javascript or jquery?

By: The Css Ninja

The Css Ninja — Tue, 20 Jul 2010 00:24:44 +0000

@Idiot –

Any browser that says they support the geolocation API will abide by the specification which states:

The latitude and longitude attributes are geographic coordinates specified in decimal degrees.

So it should always supply the coordinates in decimal degrees. Trying to work with any other format would be a nightmare in javascript.

By: Idiot

Idiot — Mon, 19 Jul 2010 17:42:25 +0000

I do not have an iPhone, so I am going on faith here. I assume that the latitude and longitude are returned in decimal format?

As you know, there are three different GPS formats: decimal (45.758759), degrees-minutes (N 19° 38.416), and degrees-minutes-seconds (N 19° 38′ 13”).

If the return values of the coordinates are not in decimal format, please let us know. Thanks!

By: The Css Ninja

The Css Ninja — Mon, 05 Jul 2010 03:29:50 +0000

@Koyetsu - Google has a reverse geocoding service just pass your latlng to that and it will return JSON

By: koyetsu

koyetsu — Tue, 29 Jun 2010 23:17:43 +0000

Ok, so pulling the gps location isn’t hard…what i can’t seem to find, anywhere is example code of how in the heck you turn it into a city/state location. i don’t wanna map all i need is a fricken plain text “New York City, NY” dropped into a text box. and i can’t seem to find anything like that anywhere. if someone can help me out i would appreciate it. i’m sure it has to do with reverse geocoding but about half the sites i found on that don’t work and the rest don’t work either! hehe.
Let me know if you can point me at a resource or have sample code to share.

koyetsu AT yahoo DOT com