如何使用 M7 协处理器计算 iOS 设备的行驶距离、速度、持续时间？
我参考了苹果的 CMMotionActivityManager 文档 https://developer.apple.com/library/ios/documentation/CoreMotion/Reference/CMMotionActivityManager_class/Reference/Reference.html#//apple_ref/doc/uid/TP40013503
它提供对设备存储的运动数据的访问，我们得到的数据是这样的：
CMMotionActivity@14074.912282,<startDate,20140303 10:09:40
+0000,confidence,1,unknown,0,stationary,0,walking,1,running,0,automotive,0>
CMMotionActivity@14077.466468,<startDate,20140303 10:09:43
+0000,confidence,0,unknown,0,stationary,0,walking,0,running,1,automotive,0>
CMMotionActivity @ 14080.024116,<startDate,20140303 10:09:46
+0000,confidence,1,unknown,0,stationary,0,walking,0,running,1,automotive,0>
CMMotionActivity@14082.582084,<startDate,20140303 10:09:48
+0000,confidence,2,unknown,0,stationary,0,walking,0,running,1,automotive,0>
因此，不使用 GPS /仅依靠 M7 数据，我可以计算（例如跑步）行驶距离、跑步持续时间、速度等。