iOS touch input stuttering

Noticable frame jumps and frame freezes on ios with simple touch input

• Recordings 240 FPS
• Introduction Video
• Raw video data

Project information

Problem

• Triggering the event system with touches on a dummy button creates frame problems
• The frame problems are either Frame freezes or frame Jumps
• boh of them are quite subtle, but noticable once you’re trained to see them
• Frame Jumps (leaving out one frame) seems to be more common than frame freezes (in Unity 5.6 at least)
• Most significant problems on iPad Pro
• On GLES3 the problem seems to be less frequent than on Metal

Test Scenario

• Unity 5.6.0f2
• XCode 8.3 (8E162)
• OpenGLES2, OpenGLES3 and Metal graphics API
• il2CPP
• Gamma color space

Results (v0.2)

Lost frames - (Without Tapping / With Tapping)

	Metal+Xcode	Metal
iPad Pro	(0.472 / 6.850)	(1.519 / 3.997)
iPhone SE	(0.223 / 0.8135)	(0.234 / 0.800)
iPhone 6s Plus	(0.403 / 1.943)	(0.465 / 1.053)

Additional Tests

• Tested with Unity 5.5.1p1
• Tested with XCode 8.2.1, 8.3 beta 2

How to reproduce?

• Clone the project
• set Build Target to iOS and release, disable development build
• Build & Run Project
• Install the app
• Detach the device from the computer
• Run once without hitting the Tap! button
• Run once with hitting the Tap! approximately twice a second
• Calculate the difference between the two outcomes