Those familiar with existing prototypes say Apple's current plans call for both the new 4.7-inch model (N71) and the 5.5-inch "iPhone 6s Plus" (N66) to gain Force Touch and haptic feedback, a capability Apple debuted alongside the "Taptic Engine" when Apple Watch was announced in September. Their arrival on the iPhone product line will come roughly one year later, falling in line with the company's historical pattern of first debuting new cutting edge technology on one iOS device (iPhone) before extending it to another (iPad) the following year.
Force Touch uses tiny electrodes around the flexible Retina display to distinguish between a light tap and a deep press, and trigger instant access to a range of contextually specific controls — such as an action menu in Messages, or a mode that allows you to select different watch faces — whenever you want. Apple calls it the most significant new sensing capability since Multi‑Touch.
One person, 'extremely knowledgeable' about Apple's future plans, said the company toyed with putting Force Touch in the iPhone 6 but 'calibration' issues resulted in the feature getting pulled.
The iPhone 6s may also have the ability to modulate its vibration motor's amplitude and duration, so similar to the Apple Watch, notifications might be able trigger a tapping sensation.
Finally, sources say that packing in an extra camera would require a modification of the iPhone housing, 'which will not happen this year'.
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