Is it possible to utilize button-hold on mobile phone as a trigger for some programmed action? E.g. my app runs in background and it is programmed to open up if I hold both volume up and volume down buttons for 3 seconds.
I want to make iPhone/Android app. I haven't choose any framework yet, it's a question of technical possibility of such an idea, but I'll probably use objective-C/Swift as I have an iPhone.