Xcode 11.6 simulator performance not matching hardware

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Created Aug ’20

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I am using the Stanford iOS programming course spring 2020 to learn Swift UI and finding that animation delays are not coming close to match performance when comparing my iPad Pro to the iPad Pro simulator. My iPad is running iOS 11.6.1 and the code is targeted to 11.6. The simulator is far slower at performing the animations than my hardware. I see no hope of ever being able to use the simulator to tune code performance for multiple targets with it working this poorly. Is this being seen any where else. The animations are very nice and easy to code but without tuning they are unusable.
Any thoughts?

Answered by travis78701 in 629901022

Firstly, make sure you don’t have "Slow Animations" turned on under the Debug menu in simulator. Secondly, I don’t think you should expect performance to be accurate. It’s simply a simulator.

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Answer 1

travis78701 OP

Aug ’20

Accepted Answer

Firstly, make sure you don’t have "Slow Animations" turned on under the Debug menu in simulator. Secondly, I don’t think you should expect performance to be accurate. It’s simply a simulator.

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Answer 2

JackReigh OP

Aug ’20

Thanks,

The animations are not slow duration 0.75 to 1.5 but on simulations that is 15 to 1 in performance. Multiple things are happing on 1 card flipping and having things rotating on one surface. Without real hardware this is impossible. I would also like to know is looks good on multiple targets. I not sure how to trust using only one real target represents all hardware when testing. Simulation these things are completely untestable. I do know how important testing have written embedded software for aircraft for 47 years. I would expect debug to slow things down.

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Answer 3

travis78701 OP

Aug ’20

There is no substitution for testing on a real device, especially if you have timing-sensitive code. Over the years, the simulator has had bugs that aren’t present on devices, and vice versa. Use it as a convenience, but not as an indicator of real world performance. “use the simulator to tune code performance’ simply isn’t practical.

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Answer 4

Claude31 OP

Aug ’20

Does it improve is you change scheme to Release instead of debug and disable debug executable ?

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Answer 5

JackReigh OP

Aug ’20

Travis You hit the nail on the head but I never remember touching the debug menu ever. That did make the simulation very close to what I see on the real hardware. Thanks. I even see iPhone 11 sim looking like I would be happy with the performance on a real hardware one. Thanks again, I saw several checks on that menu I would never have said I ever selected.

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