After it was found on Friday that developers weren’t able to make use of the ProMotion on iPhone 13 Pro, Apple has released documentation on how to implement variable refresh rates. The guide at Apple’s Developer website under the Core Animation category titled “Optimizing ProMotion Refresh Rates for the iPhone 13 Pro and iPad Pro” educates app developers to take advantage of the new display
Apple says apps may already be able to take advantage of the new refresh rate without any changes. And, as some framework animation features handle frame pacing automatically such as the UIkit, SwiftUI, SpriteKit, and CAAnimation, developers wanting to specify timing can make use of the Core Animation’s CADisplayLink.
The guide goes on to explain how the refresh rate on a ProMotion Display behaves differently. ProMotion display cannot show refresh rate at a specific rate. Instead, the system picks up the actual rate from the developer’s app.
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The iPhone 13 Pro and 13 Pro Max feature ProMotion Display capable of showing content at variable refresh rates ranging from 10Hz, 12Hz, 15Hz, 16Hz, 20Hz, 24Hz, 30Hz, 40Hz, 48Hz, 60Hz, 80Hz, and 120Hz.
Apple presses to use lower refresh rates whenever possible to reduce significant power consumption as much as possible.
To enable faster refresh rates (above 60Hz), Apple advises adding the following key to the Info.plist file to enable full range refresh of rates for the CADisplay callbacks and CAAnimations in the app.
<key>CADisableMinimumFrameDurationOnPhone</key><true/>