Coremotion Frames-Accelerometers and gyroscopes

The iOS accelerometer is a triaxial accelerometer that monitors motion and gravity in three-dimensional space.

three-axis coordinate system:

* When the top of the phone is up, it is on the phone screen, the phone screen to the left is the X axis positive direction.

* Along the phone screen upward is the Y axis positive direction.

* Vertical screen outward is the z axis positive direction.

When the phone is stationary, the gravity of the earth will give the phone 1g acceleration.

Coremotion Frames-Accelerometers and gyroscopes