ios The time it takes to call a function in a for loop is gradually reduced

Question

The following is the code and time-consuming screenshot

I call a C language function in a for loop. It takes a long time at first, then it decreases with each call, and finally stabilizes within a small range.
How to explain this situation? Is it optimization of the iOS platform or something else?
Thank you very much~

Answer 1

It should be related to method caching. You can understand this process from objc_msgSendmessage distribution.