// When the user taps the status bar, the scroll view beneath the touch which is closest to the status bar will be scrolled to top, but only if its `scrollsToTop` property is YES, its delegate does not return NO from `shouldScrollViewScrollToTop`, an…
在官方文档中是这样介绍beginUpdates的 Call this method if you want subsequent insertions, deletion, and selection operations (for example, cellForRowAtIndexPath: andindexPathsForVisibleRows) to be animated simultaneously. This group of methods must conclude with…