How Does A Remote Shutter For Camera Work On Android/ios?

I've recently ran across a remote shutter for in-built camera app using bluetooth on Android/iOS. Here's an example link of the product that I found: Link (Not here to advertise,

Solution 1:

The selfie stick remotes are essentially tiny Bluetooth keyboards with just two keys. One is the "Volume Up" key to trigger iOS' native Camera shutter and the other key is "Enter" to trigger Android.

Solution 2:

When the camera app is running, both Android and apple utilize the volume up button to signal the shutter event.

With this in mind, all an external device needs to do is trigger the same volume up event which in turn triggers the shutter event.

This then allows for a remote shutter button whether the button is plugged into the audio/mic port, or connected via bluetooth.

The audio mic port may be different between android and iphone. I plugged an external camera button into my android and rather than it triggering the volume up event, it triggered the back button in the mp3 player.

Hope this helps you out.