UIScrollView

UIScrollView is a subclass of UIView that enables scrolling and zooming of content that is larger than the scroll view’s bounds. It handles touch-based panning and deceleration and is commonly used to present long content, interactive canvases, or image galleries within an iOS app.

Key properties include contentSize, which defines the scrollable area in points; contentOffset, the x and y position of the visible region; and isScrollEnabled, which toggles scrolling. Other commonly adjusted settings are pagingEnabled for page-like scrolling, showsHorizontalScrollIndicator and showsVerticalScrollIndicator, bounces, and contentInsets that add insets around the content. Since iOS 11, you can also use contentInsetAdjustmentBehavior to control how safe areas affect insets.

Zooming is supported by setting minimumZoomScale and maximumZoomScale and by providing a view to zoom via the UIScrollViewDelegate method viewForZooming(in:). The zooming behavior is reported with scrollViewDidZoom, and the current zoom scale is exposed as zoomScale.

Auto Layout can be used with UIScrollView via the contentLayoutGuide and frameLayoutGuide (iOS 11 and later) to constrain content. Before constraints, contentSize was set manually. The scroll view lays out its content within its bounds and adjusts scrolling accordingly.

UIScrollView uses the UIScrollViewDelegate protocol to notify about scrolling events, dragging, deceleration, and zooming. Implementing methods such as scrollViewDidScroll, scrollViewWillBeginDragging, scrollViewDidEndDecelerating, and scrollViewDidZoom enables custom reactions to user interactions.

Typical usage involves adding the scroll view to a view hierarchy, configuring its frame or constraints, setting a delegate, and adding a content view or subviews inside the scroll view whose layout determines the contentSize (or constraints define the content layout).