3D Touch for iPhone 6S and iPhone 6S Plus has a very interesting and useful function to access the applications open in the terminal much faster, it is copied after one offered in the past by the well-known tweak zephyr, but also many others after him.
Although it took about 3 years for Apple to natively implement this functionality in iOS 9, using 3D Touch on iPhone 6S and iPhone 6S Plus you will be able to switch from one iOS application to another by simply pressing and sliding your finger from left to right, a stronger press without completing the gesture opening the task switcher.
The gesture itself is not difficult to do once you get used to it Touch 3D, and I still haven't gotten used to it completely, so you'll see that I don't master it completely, but after you get used to the system, you'll make the transition from one application to another very easy.
I think this is one of the extremely useful functions of 3D Touch for iPhone 6S si 6S iPhone Plus and I think that Apple could offer more from it by closing all applications in the background or accessing some favorite applications by making various other gestures.
However, until the moment when Apple gives us the possibility to customize 3D Touch, I am happy to see that we have at least this functionality offered in its very simple form for iPhone 6S and iPhone 6S Plus.
Of course, through Cydia you can get the same functionality with just simple swipes, but you must have a jailbreak first.
