The force of the touch, where a value of 1.0 represents the force of
an average touch (predetermined by the system, not user-specific).
The force reported by Apple Pencil is measured along the axis of the
pencil. If you want a force perpendicular to the device, you need to
calculate this value using the altitude_angle value.
A value of 0 radians indicates that the stylus is parallel to the
surface. The value of this property is Pi/2 when the stylus is
perpendicular to the surface.
If the platform reports the force as normalized, we have no way of
knowing how much pressure 1.0 corresponds to – we know it’s the maximum
amount of force, but as to how much force, you might either have to
press really really hard, or not hard at all, depending on the device.
Returns the force normalized to the range between 0.0 and 1.0 inclusive.
Instead of normalizing the force, you should prefer to handle
Force::Calibrated so that the amount of force the user has to apply is
consistent across devices.