addChild

addChild is a method name used across several programming frameworks to attach a node, object, or component as a child of another within a hierarchical structure. It is commonly found in scene graphs, user interface trees, and other tree-like data models. The exact behavior depends on the language and framework, but typical semantics involve creating a parent–child link, updating the child’s parent reference, and adding the child to the parent’s list of children. In many implementations, attempting to attach a node that already has a parent will detach it from its previous parent or raise an error.

In user interface and scene graph contexts, adding a child often implies that the framework will recalculate layout, rendering order, or lifecycle events. The operation may affect visibility, transforms, and event propagation, and it can trigger notifications to listeners about structural changes. Some environments expose additional options, such as whether to preserve the child’s world transform or to inherit certain properties from the parent.

Examples in different ecosystems illustrate the range of usage. In iOS and UIKit, adding a child view controller with addChild(_:) establishes containment of the child controller, after which the child’s view is added to the view hierarchy and the child is informed with didMove(toParent:). In Godot, Node.add_child(child) attaches a node to the scene tree, where the child participates in rendering and processing. In generic tree data structures, addChild typically appends a node to the parent’s children collection, potentially returning a reference to the new child.

Considerations include lifecycle management, ownership and memory considerations, prevention of cycles, and thread-safety concerns. See also: appendChild, removeChild, attach, detach, scene graph.