The new iPhone 13 Pro models that launched today are equipped with ProMotion display technology, which allows for adaptive refresh rates ranging from 10Hz all the way to 120Hz, which is ideal for scrolling through content, gaming, and more, because it makes for a smoother viewing experience.
Though there's a 120Hz maximum refresh rate, App Store developers have found that most app animations are limited to 60Hz, which results in an uneven viewing experience for users. As noted by 9to5Mac, ProMotion works at the full 120Hz for scrolling and full-screen transitions, but animations are limited to 60Hz.
So when you're scrolling through your Twitter timeline, for example, you'll see the smooth ProMotion experience, but animations at 60Hz mean other interactions are noticeably less smooth. Apollo developer Christian Selig has already seen complaints from customers.
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/t3MeM9cj0E — Christian Selig (@ChristianSelig) September 24, 2021
Selig speculates that Apple added the 60Hz limitation to preserve battery life on the iPhone models because on the iPad Pro models that also support ProMotion technology, there is no limit and all animations run at 120Hz.
Note that this isn't the case on iPad Pros, those do use 120 Hz for all animations. See attached. I assume this is a purposeful battery life optimization choice on iPhones. 🔋 pic.twitter.com/Utg0oaDzdi — Christian Selig (@ChristianSelig) September 24, 2021
Apple's own apps appear to run at up to 120Hz at all times, so there's also a possibility that this is a bug or an issue that Apple plans to address in a future update.
Update: Apple says that there is a special declaration developers need to use in order for their apps to take advantage of the higher frame rates, but that there is also a Core Animation bug that will be addressed in an upcoming update.
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