What does the iPhone mean to be a metal detector? --Why the iPhone can't be heard anymore?

The appeal and strength of the iPhone is that you can understand how to use it without reading the manual. However, there are times when you think you know it but you don't understand it correctly. In this section, we will explain in an easy-to-understand manner "why the iPhone can't be heard anymore". This time, we will answer the question, "What does it mean for the iPhone to become a metal detector?"

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There are various types of compasses, but the most common type that utilizes the properties of magnets shows a sensitive reaction to the surrounding magnetism. It is well known that it reacts to permanent magnets and iron products, but it also applies to buildings using steel frames and electronic devices such as mobile phones.

The current model of iPhone has a built-in magnetic sensor that detects weak magnetism such as geomagnetism. The function to measure the direction using the magnetic sensor is "electronic compass", which is used in apps such as "map" and "compass" where the current location and direction are important.

This electronic compass has a framework in place (Core Location) that can be used for app development, and in fact many third parties publish their apps. Many access the functionality of the electronic compass for the purpose of measuring orientation, but there are exceptions. That is the so-called "metal detector app".

The metal detector app is thought to check how much the iPhone's built-in electronic compass reacts to the surrounding magnetism to determine if there are permanent magnets or iron products around it. The iPhone's standard app doesn't have such a feature, but the electronic compass, like the compass that uses a permanent magnet, reacts to the surrounding magnetism, so it's a nod to the principle of operation.

When I actually tried it with a third-party app called "Metal Detector", it showed a clear reaction when I approached the kitchen knife. It reacts more strongly to devices that use magnets such as speakers. If you adjust the sensitivity, it will react to small metals. Although there are still doubts about its practicality, the answer to the question of whether it works as a metal detector is "YES".