hitTestwithEvent

hitTest:withEvent: is a method defined on UIView in UIKit and is used to determine which view in the current view hierarchy should receive a touch event. It is part of the event delivery process that routes touches from the window to the appropriate view.

During event dispatch, hitTest:withEvent: is called on the root view and recursively traverses the hierarchy to find the target view. The method first checks basic eligibility: the receiver must be in a window, not hidden, userInteractionEnabled, and have an alpha greater than 0.01. If these conditions are not met, the method returns nil, indicating no hit.

If eligible, the method iterates over the receiver’s subviews in reverse order (frontmost first). For each subview, it converts the touch point from the receiver’s coordinate system into the subview’s coordinate space and calls hitTest:withEvent: on that subview. If any subview returns a non-nil result, that view is returned as the hit-test target.

If no subview handles the event, the receiver itself may be chosen if it can handle touches. This is determined by pointInside:withEvent:, which checks whether the point lies within the view’s bounds, and by the receiver’s ability to receive events. If true, hitTest:withEvent: returns self; otherwise it returns nil.

Override notes: Developers may override hitTest:withEvent: to customize how touches are routed, such as ignoring touches in certain regions, forwarding touches to another view, or implementing specialized hit-testing behavior in composite views. It is often used in conjunction with the standard touchesBegan:, touchesMoved:, and touchesEnded: methods to implement custom interaction logic.