SceneKit, sometimes rendered Scene Kit, is a 3D graphics application programming interface (API) for Apple Inc. platforms written in Objective-C. It is a high-level framework designed to provide an easy-to-use layer over the lower level APIs like OpenGL and Metal. SceneKit maintains an object based scene graph, along with a physics engine, particle system, and links to Core Animation and other frameworks to easily animate that display. SceneKit views can be mixed with other views, for instance, allowing a SpriteKit 2D display to be mapped onto the surface of an object in SceneKit, or a UIBezierPath from Core Graphics to define the geometry of a SceneKit object. SceneKit also supports import and export of 3D scenes using the COLLADA format. SceneKit was first released for macOS in 2012, and iOS in 2014.
SceneKit maintains a scene graph based on a root object, an instance of the class SCNScene. The SCNScene object is roughly equivalent to the view objects found in most 2D libraries, and is intended to be embedded in a display container like a window or another view object. The only major content of the SCNScene is a link to the rootNode, which points to an SCNNode object.
SCNNodes are the primary contents of the SceneKit hierarchy. Each Node has a Name, and pointers to optional Camera, Light and Geometry objects, as well as an array of childNodes and a pointer to its own parent. A typical scene will contain a single Scene object pointed to a conveniently named Node (often "root") whose primary purpose is to hold a collection of children Nodes. The children nodes can be used to represent cameras, lights, or the various geometry objects in the Scene.
A simple Scene can be created by making a single SCNGeometry object, typically with one of the constructor classes like SCNBox, a single SCNCamera, one or more SCNLights, and then assigning all of these objects to separate Nodes. A single additional generic Node is then created and assigned to the SCNScene object's rootNode, and then all of the objects are added as children of that rootNode.
SCNScenes also contain a number of built-in user interface controls and input/output libraries to greatly ease implementing simple viewers and similar tasks. For instance, setting the Scene's autoenablesDefaultLighting and allowsCameraControl to true, and then adding an object tree read from a COLLADA file will produce viewable content of arbitrary complexity with a few lines of code. The integration with Xcode allows the Scene itself to be placed in a window in Interface Builder, without any code at all.