case always // contentInset is always adjusted by the scroll view's safeAreaInsets} 新增safeAreaInsets: UIEdgeInsets属性 只读属性,为了配合contentInsetAdjustmentBehavior使用 新增adjustedContentInset: UIEdgeInsets属性 只读属性,这个属性会根据safeAreaInsets的变化而变化 UIScrollViewDelegate新增scrollViewDidChang...