Given the case that you can live with delta movements, you can use “quaternion difference” operation. Let’s say you have a previous rotation as quaternion called q1 and the current one q2. Then you can calculate the delta dQ between them so that q2 = q1*dQ is valid. All you have to do is build … Read more
RunKeeper actually does use the audio trick to stay awake. If you open up the app package and check their Info.plist you will see that it registers for the background audio mode. This is how they pull off periodic audio notifications of your distance, speed, and pace. It is also how they stay awake during … Read more
All the advice about the wisdom (or lack thereof) in guessing about motion states from location data still applies. But regarding your update about Core Motion and M7… Yes, you can use Core Motion on devices with an M7, M8, M9, etc motion coprocessor(*) to get an indication of whether the user might be driving. … Read more
To unravel this I’ve spent a bit too much time digging through the Apple docs. There are three ways of obtaining magnetometer data 1/ Core Motion framework CMMotionManagers’s CMMagnetometer class 2/ Core Motion framework CMDeviceMotion CMCalibratedMagneticField property 3 / Core Location framework CLLocationManager’s CLHeading 1/ supplies ‘raw’ data from the magnetometer. 2/ and 3/ return … Read more