As spotted by 9to5Mac, the 120Hz ProMotion display on the new iPhones isn't performing as expected on some third-party apps, with software sometimes reverting to 60Hz on animations. Fortunately, Apple is aware of the issue and says a fix is coming soon — although there's no exact timeframe as of now.
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The ProMotion display — which can jump between 10- and 120Hz depending on what’s required — is the star of this year’s top-end iPhones. In his iPhone 13 Pro review, our phones editor Jordan Palmer was pretty smitten.
“Once you experience a 120Hz display, it’s hard to go back to a 60Hz one,” he wrote. “The same holds true for the iPhone 13 Pro, which has a noticeably smoother screen than the 12 Pro,” he continued, noting that the crisp animations and smooth performance make for “an extremely premium experience.”
It's therefore a big shame that the displays aren't working properly with some third-party apps, albeit one that wouldn’t be such a big deal if they were consistently stuck at 60Hz and therefore 60fps.
However, as 9to5Mac notes, some apps inadvertently combine 120Hz scrolling and full-screen transitions with 60Hz animations, which leads to an uncomfortably jarring experience for the user. It’s something that’s hard to miss, as this comment on the Apollo app demonstrates:
Am I correct in seeing that UIView.animateWithDuration APIs aren't clocked at 120Hz on iPhone 13? On UIScrollView, system ones, and Metal by the looks of it, rest is still 60Hz? pic.twitter.com/t3MeM9cj0ESeptember 24, 2021
Initially, this third-party restriction appeared to be deliberate, with an examination of the iOS 15 code indicating that first-party Apple apps were exempt from caps, but Apple has since clarified that this isn’t intentional after all. The company told The Verge that two things can cause the issue: one on the developer side and the other on Apple's.
The first is that developers need to update their apps with a flag declaring that they support 120Hz mode, something that can be done via an additional entry to an app’s Info.plist key. Apple says documentation clarifying this will be published soon.
The second is a good old fashioned bug. Some animations built using Apple’s Core Animation tech have an issue that will soon be fixed via a software update.
Annoying though it might be, we wouldn't suggest the issue should put you off buying either the iPhone 13 Pro or Pro Max. Indeed, we're hugely impressed with all four of the iPhone 13 family of handsets: three of the four have entered our list of the best phones you can buy, and our iPhone 13 battery test shows a marked improvement on a weak spot of the previous generation.
- More: iPhone 13 Pro Max review