Back in 2014, just before the release of the iPhone 6 and 6Plus, Scott Hurff made an interesting observation about the iPhone screen sizes. Hurff’s observation was that the natural touch zone for an iPhone has shrunk down after the introduction of larger screen sizes and that it’s harder to reach the top of the screen.
Scott’s observation has gained a lot of attention since then and the touch zones’ image he posted back in 2014, has been circulated amongst designers, and pretty much forms the basis of the idea that the navigation should be bottom heavy.
While the bottom heavy navigation is a great idea, and one that’s been explored often. I’d argue that the entire top area isn’t all that unusable.
Essentially, the touch zones are based on an assumption that the thumb is anchored to the bottom right corner of the display. The bottom right corner anchor makes sense if it’s an iPhone 4S, or an iPhone 5s. That sort of grip, isn’t ideal for the iPhone 6 or 6Plus, as it’d disturb the balance of the phone if the thumb were to try and reach at the top. Instead, people grip their larger phones differently, which tends to shift their thumb anchor a little upwards and more towards the centre than the bottom of the screen. Touch Zones look different if the position of hand is taken into account as well.
If I were to pick the touch zone on the right, the changes made to the UI in iOS 11 would make some more sense. (The top navigational bar containing bold title, but then offering the search bar or some other interact-able element exactly below the title, instead of bottom of the screen).
While it makes sense to shift some of the elements of the navigation bar downwards, shifting the entire navigational structure to the bottom would potentially leave some interact-able area at the top
While I don’t have enough data to prove which one of the touch zones more accurately represents the ideal zones for thumb-reach, I hope more and more designers take the hand position into account when using touch zones.