bear on
When using the compass, the magnetic phone case will have an effect, and it has no effect on other functions or internal data.
At present, most mobile phone devices in the market, there will be a number of very small but important role of magnets. The latest generation of Apple Watches, for example, uses a magnetic inductive wireless charging system. In daily use, the external role of the magnet is a static magnetic field, not an alternating magnetic field, so it does not produce an electromagnetic field and will not affect the use.
When using a compass, because the mobile phone needs a magnetic field to determine the direction. If there is a strong external magnet, it will affect the magnetic field of the phone. As a result, magnets can temporarily interfere with the digital compass and magnetometer in smartphones, which can cause directional misalignment.