Sunday, July 09, 2017

Why Doesn't The Compass Work in Some iPhone Apps?

As a writer of apps—such as TV Towers USA—which rely on the device's compass, I periodically would hear from users who don't see the compass in my apps. This confused me as they would also report the built in iPhone compass app working. And the apps worked perfectly well for me.

I've finally figured out what is going on. At some point, the users had turned off compass calibration in their location privacy settings. And since my apps are set to request calibrated data, the app gets no compass data at all.

So, to fix, open the iOS Settings app.

Tap the Privacy item:

Tap the Location Services privacy item:
Tap the System Services item (way down on the bottom):

If Compass Calibration is disabled, then this was likely your problem. Enable it.

And, I hope, your app will go from not having an active compass, to having one:

I should look into detecting this condition and warning the user. Hope this helps.

Thursday, February 23, 2017

True North and the iOS Compass App

I recently got a 2 star review for my TV Towers USA app.

This would be a nice app if it pointed in the right direction!  Most of the time its sense of

direction differs from the compass app.

How can that be? ⭐⭐

Well, the short answer is that the iOS compass app tries to act like an old timey compass where North means magnetic North, and TV Towers USA instead is displaying the direction based on North being the Earth's north pole. You can go into the settings for the Compass app, turn on "True North", quit the Compass app and from then on, it will act like a super-compass that can calculate the location of the North Pole based on both magnetism and location.

I've put together a short video to describe the situation, and how to configure the iOS compass app.