CMMotionMagager可使您绕iPhone的轴以及重力方向加速。通过将这两者相乘，您可以计算出从地球到地球的加速度。这是相乘结果的长度。我正在使用Ray Wenderlich的3D Vector工具。

CMMotionMagager gives you acceleration about the iPhone's axes and also the direction of gravity. By multiplying these two you can calculate the acceleration from/to the earth. It's the length of the result of this multiplication. I'm using Ray Wenderlich's 3D Vector utils.

在您的GameViewController中：

In your GameViewController:

  var motionManager: CMMotionManager!

在GameViewController.viewDidLoad中：

In GameViewController.viewDidLoad:

  motionManager = CMMotionManager()
  motionManager.startDeviceMotionUpdates()

在GameScene中：

In GameScene:

 override func update(_ currentTime: TimeInterval) {

    if let deviceMotion = motionManager.deviceMotion {

    let gravityVector = Vector3(x: CGFloat(deviceMotion.gravity.x),
                                y: CGFloat(deviceMotion.gravity.y),
                                z: CGFloat(deviceMotion.gravity.z))

    let userAccelerationVector = Vector3(x: CGFloat(deviceMotion.userAcceleration.x),
                                         y: CGFloat(deviceMotion.userAcceleration.y),
                                         z: CGFloat(deviceMotion.userAcceleration.z))

    // Acceleration to/from earth
    let zVector = gravityVector * userAccelerationVector
    let zAcceleration = zVector.length()
  }

要知道运动方向：

sign(Double(zVector.x * zVector.y * zVector.z))

当您不再需要它时，请不要忘记调用.stopDeviceMotionUpdates（）。

Don't forget to call .stopDeviceMotionUpdates() when you don't need it anymore.