My colleague showed me this function called AssistiveTouch (thanks to Azali) in the office this morning. I was amazed. Just now I managed to activate this function to my iPhone. Here are the steps:
Launch the Settings app.
Scroll all the way down and tap AssistiveTouch then toggle it on. (You’ll know its working, when you see a floating button appear on your screen.)
Turning on AssistiveTouch causes a semi-transparent button to appear. Tapping this button gives you access to the same functions as the hardware buttons, such as volume up or down, as well as several gesture types, like pinch to zoom. You can even set custom gestures.
Have fun :)