A possible bug in iOS 9 appears to affect certain augmented reality apps running on the new iPhone 6s. Apps that make use of the device’s compass and gyroscope data are affected.
AppleInsider reader Frank experienced the problem first hand with popular stargazing app Sky Guide, which relies on iPhone’s advanced sensor suite to power an augmented reality function that transforms the device into an interactive map of the night sky. Under normal conditions, users point their iPhone up toward the sky to see an onscreen view of stars, planets, constellations and more, but on iPhone 6s running iOS 9 — including the latest iOS 9.0.1 update — the map drifts uncontrollably.
Sky Guide developer Fifth Star Labs confirmed to the publication that the issues affecting the app’s “Compass” feature are confined to the iPhone 6s, and does not affect older hardware. While other third-party apps are also seeing issues, Apple’s own Maps app appears to function properly, indicating the issue could lie in the iOS API for the functions. Fifth Star Labs is reportedly working on a fix for the issue.
A similar issue was reported a few years back, when iPhone 5s owners reported faulty readings from the iOS 7 Compass app. It was believed at the time that a switch in accelerometer suppliers caused the app to improperly calibrate the device. Apple later issued a fix.
Teardowns of the iPhone 6s and iPhone 6s Plus indicate the handsets use the same InvenSense 6-axis gyroscope/accelerometer chip and Bosch Sensortec 3-axis accelerometer module as was used in the iPhone 6 & 6 Plus. However, the M9 motion coprocessor is now embedded in the A9 system on a chip which powers the new handsets. The M9 acts as a data hub for the iPhone’s numerous sensors.