how accessibilityApplyScrollContent works

hi, In my project, I try to use UIAccessibilityPostNotification (UIAccessibilityScreenChangedNotification, A) method focusing on A, But will call accessibilityApplyScrollContent: sendScrollStatus: animateWithDuration: AnimationCurve, which triggers the scrolling method of A's superView (scorllView). I didn't know what was going on, so I wanted to understand how it worked.I will be very pleased If you could reply to me