It took 3 Years to develop A11 Bionic Chipset

Apple A11 Bionic
The launch of iPhone 8 and 8 Plus, as well as iPhone X at the same time became Apple's momentum in introducing its newest chipset, the A11 Bionic.

In a recent interview SVP of Worldwide Marketing Apple Phil Schiller and SVP of Hardware Technology Apple's Johny Srouji called that A11 Bionic developed within three years. Means development began since after the iPhone 6 shipped, ie in 2014.

"Neural engine pinned, this is a fight we made for three years," said Srouji.
Neural engine is a system that is in A11 Bionic chipset in charge of building artificial neural network for Face ID feature. This feature is presented as a replacement for the Touch ID for iPhone X.

Its function is nothing but a face scanner and confirms the identity of the user without having to press the button.
Benchmark Geek Bench's site notes that A11 Bionic's performance is almost equivalent to the MacBook Pro. In testing, the A11 Bionic chipset recorded a score of 1,141 for single-core. While the MacBook Pro is known to score 1,592 for single-core.