Reason for setting the display rect of uiscrollview but does not enter the delegate method of didscrollview, uiscrollviewdelegate

Reason for setting the display rect of uiscrollview but does not enter the delegate method of didscrollview, uiscrollviewdelegate

To preview a local image, scrollview is automatically rolled to the view of the next image when the current image is deleted. Use this method to switch to scrollRectToVisible. The scrollViewDidScroll method is automatically refreshed to achieve the image switching effect. Note that when the rect parameter passed to scrollRectToVisible is the rect displayed in the current scrollview, The scrollViewDidScroll method is not entered. Therefore, if the expected results are not met, call [_ scrollview setContentOffset: CGPointMake (0, 0) animated: NO] First after deletion. This method offsets the scrollview displacement, then, call the scrollRectToVisible method to enter scrollViewDidScroll to refresh the image.

Note that the scrollViewDidScroll method is also enabled when setframe is set for scrollview.