It's largely the same pressure-sensitive screen technology that appears in the Apple Watch and Apple Watch Series 2 (under the name Force Touch), but whereas your watch can distinguish between two degrees of pressure - a standard tap and a harder Force Tap - the 3D Touch-equipped iPhone 6s and 7 offers three. This opens up considerable potential for new interface features.
In this article we're going to look at the most useful 3D Touch-enabled tricks, tips and new features that iPhone 6s and iPhone 7 owners can now enjoy.
3D Touch will be activated by default on your new iPhone 6s or later, but you can fiddle with a few settings or even turn it off (madness!) by going to Settings > General > Accessibility, swiping down to the unlabelled fourth group of options and tapping 3D Touch. Then adjust your sensitivity and once you're ready, turn to the next slide and we'll start exploring this new suite of features.
Control Centre in iOS 11
The Control Centre in iOS 11 (which at time of writing is available in beta only) gets a decent revamp. For one thing you can customise what appears in it; for another you can do use 3D Touch to open up additional options.
Do a deep press on some of the options and you'll see a popup menu of additional quick actions. On others it will open the relevant app. Play around and get a feel for the new features.
Phone, FaceTime, Messages
Go to your Home screen and do a harder press on the icon for the Phone app (not just a normal tap/press - firmly push into the screen). You'll see that a useful little mini-menu pops up, offering the ability to call one of your more frequently called contacts, or to create a new contact.
Do a 3D Touch press on the FaceTime or Messages app icons and you'll see similar quick-jumps to recently or frequently contacted friends - a very helpful means by which you can go straight to a call with a loved one without going into the app, searching through contacts and so on.
(If you want to edit the quick-actions that come up in the mini-menu when you do a harder press on the icon for Phone, Messages or FaceTime, incidentally, take a look at our quick tutorial: How to edit the 3D Touch shortcut menus for Phone, Messages & FaceTime.)
Since the launch of iOS 10 it's been possible to stipulate the order in which apps are downloaded if you're installing more than one at once. Use a 3D Touch hard-press on the semi-downloaded app's icon and you'll get the option to Prioritise Download.
Read more: iOS 10 new features
Track your Uber driver
3D Touch your Uber notification and you'll see the driver's progress on a map, with the option to send them a message.
Weather gets a new shortcut from the home screen - 3D Touch to see more details about current and future weather conditions.
The three main Apple communication apps (we're leaving aside Mail for the time being, but we'll come back to it in a moment) offer the most basic execution of the 3D Touch shortcut feature, but many other Apple apps have their own equivalents. The camera app's version of this may be the most useful.
It has a mini menu that lets you jump straight to a normal photo, a video or a selfie, or even a slow-mo video. You'll never miss that important shot again.
(This is particularly useful because Touch ID has been sped up so much that we rarely see the lock screen any more. In the olden days, if you wanted to take a quick photo you would swipe up on the camera icon on the lock screen and access the camera that way.)
Shortcuts to jump straight into app actions
There are lots more shortcut menus to discover.
The App Store icon lets you go straight to an app search, and the iBooks app does something similar. (The iTunes Store currently doesn't offer this, oddly, but hopefully this is just a matter of time.) Mail, rather than offering shortcuts to specific contacts, lets you jump to individual inboxes (or start a new message). Safari lets you open a new tab, or a new Private tab, or jump to your Reading List.
There are more to find - try a force-press on any app icon to see if it has a 3D Touch-activated mini menu - but my favourite is probably Apple Maps, whose shortcut menu includes an option to get directions home. Google Maps presently doesn't have a 3D Touch menu, which might conceivably give Apple Maps a slight advantage for a while.
By the way, a few non-Apple apps have 3D Touch shortcuts - Twitter, Fantastical and Instagram are the obvious examples, but a few others such as the CARROT weather app have included this feature too - but most do not. We look forward to seeing what YouTube, Facebook, Google Maps and others come up with.
Peek and pop to preview a document without opening it
The aspect of 3D Touch that was most extensively covered at Apple's iPhone 6s launch was a linked pair of features called Peek and Pop. These allow you to preview the contents of an email, document, web page, map direction or other link, without transferring to the app involved. You can then choose to 'Pop' the item open in its relevant app if you want to know more.
The primary example given was in Mail. If you're in the Mail app and do a firmer press on an email, a preview of the message will spring up and let you check out the email without actually opening it in full. You can then do a still firmer press to make the email 'Pop' open fully, or you can release your thumb or finger to close the preview and go back to the screen you were on previously. Alternatively, you can swipe upwards and see a menu of quick actions.
Preview one app without leaving another
Peek and Pop might not seem like a huge benefit when you're working within one app, but when we start working between multiple apps you'll see the added convenience.
Take directions, for instance. If somebody sends you an address in an email, for instance, you can tap it to jump to Maps and see directions. But if you do a harder press on that address, a handy map preview will appear without whisking you out of the Mail app. You can then swipe up, press harder still to go to Maps, or release to go back.
The same principle applies with clickable web links. If you deep-press a URL in an email, say, a preview of the web page loads and then appears, and you can see what's there before (or instead of) opening it in full Safari.
There are similar preview options for lots of first- and third-party apps on the App Store. Try force-pressing links and see what you can find.
Activating cursor control on keyboard
Any time you've got the system keyboard up - in Mail, in Messages, even in third-party apps like Twitter - you can do a hard press anywhere on the keyboard and (while the individual keys grey out) you'll take control of a cursor, and can move it about pretty easily.
A simple one this, but very useful for precise text editing. (We advise you to do this with a fingertip, not a thumb. With a thumb we always find that the cursor gets a little jog out of position while we're lifting what is evidently our clumsiest digit off the screen.)
Read next: Best iOS keyboard apps
Activate app switcher
Another quick tip. Do a hard-press close to the lefthand edge of the screen - you can do this from the Home screen or from a lot of apps. You'll see the screen edges of some previously used apps. Press harder still or swipe across to the right and you'll find yourself in the app switcher, from where you can easily jump to a recently open app.
Hey, it's slightly quicker than doing a double-press on the Home button. And enjoy it while it lasts, because this feature is being removed in iOS 11.
3D Touch art & pressure-sensitive drawing
The fact that the 3D Touch screen can distinguish between different degrees of pressure is a godsend for makers of illustration and drawing apps: it unlocks the ability to create proper art.
With 3D Touch, you can draw a line across the screen and have a compatible app create a thin line if you're pressing gently and a thicker one if you're using more force: a small but fundamental step forward in touchscreen sketching.
(In the past it's been possible to achieve these effects but only crudely - by using the larger area of contact when pressing harder - or by depending on a pressure-sensitive stylus bought separately.)
This feature would be even more appealing on a tablet, which is the natural form factor for digital artists, but the implementation of 3D Touch on an iPad screen seems unlikely to happen.
The Pro offers a similar feature provided you buy the (pressure-sensitive) Apple Pencil stylus, but it doesn't have 3D Touch.
Pressure-sensitive buttons in iOS games
3D Touch holds the potential to turn onscreen elements into pressure-sensitive gaming controls - making games deeper without making their control systems any more complicated. This is a quantum leap forward.
The poster child for 3D Touch gaming at launch was AG Drive, which offers a pressure-sensitive accelerator button on the righthand side of the screen: press it normally to go at a normal speed, and press harder to kick into top gear.
The partially sighted or others who find the relatively small icons and text on smartphone screens difficult to make out are likely to enjoy the zoom feature - which isn't by any means exclusive to the new iPhones but can be activated in a slightly easier way thanks to 3D Touch.
You need to have zoom switched on to use this feature. Go to Settings > General > Accessibility > Zoom, and make sure Zoom (at the top) is switched to green. But we also want to switch on the onscreen controller icon, so tap 'Show Controller', slightly lower down, so that’s green too.
With zoom enabled, you can activate it at any time by doing a double-tap with three fingers. You can then move around the screen by swiping, again with three fingers. Double-tap again with three fingers to unzoom the screen.
That’s pretty awkward, right? So instead, use the controller with 3D Touch. Do a hard-press on it with a thumb, say, then move the thumb around to move around the screen.
You can also do a normal tap on the controller to open a menu of options, including variable zoom and the ability to hold the controller icon, but we find the 3D Touch technique the most convenient.
Read next: What 3D Touch could mean for accessibility
Activate Live Photos
Any time you see a Live Photo (you'll generally get a hint, such as a brief animation as you swipe to the image or a 'Live' icon - or set of small concentric circles - when you go to share it), a hard-press is the way to make it animate fully. It'll blur out initially then play the three seconds of footage.
The same technique applies to dynamic wallpapers, too. Give it a firm press to see the fish (or whatever) do its thing.
Read next: How to use Live Photos