# GKOctree A data structure for organizing objects based on their locations in a three-dimensional space. ``` class GKOctree where ElementType : NSObject ``` ## Overview An octree manages its structure to optimize for spatial searches—unlike a basic data structure such as an array or dictionary, an octree can find all elements occupying a specific position or volume very quickly. The octree partitioning strategy divides space into eight octants at each level, as illustrated in [Figure 1](/documentation/gameplaykit/gkoctree#1965708). When an octant contains more than one object, the tree subdivides that region into eight smaller octants, adding a level to the tree.  Octrees can be useful for many tasks in game design. For example: - Deciding which game characters are close enough to each other for interaction - Deciding which portions of a large game world need to be processed at a given time The [`GKOctree`](/documentation/GameplayKit/GKOctree) class is one of three spatial partitioning data structures that GameplayKit provides, and the only one suited to three-dimensional data. See the `GKQuadTree` class for the two-dimensional analogue of an octree, and the [`GKRTree`](/documentation/GameplayKit/GKRTree) class for different ways to organize two-dimensional data. ## Topics ### Creating an Octree [`- initWithBoundingBox:minimumCellSize:`](/documentation/GameplayKit/GKOctree/init(boundingBox:minimumCellSize:)) Initializes an octree with the specified dimensions. [`+ octreeWithBoundingBox:minimumCellSize:`](/documentation/GameplayKit/GKOctree/octreeWithBoundingBox:minimumCellSize:) Creates an octree with the specified dimensions. ### Adding and Removing Elements [`- addElement:withPoint:`](/documentation/GameplayKit/GKOctree/add(_:at:)) Adds an object to the tree corresponding to the specified point in 3D space. [`- addElement:withBox:`](/documentation/GameplayKit/GKOctree/add(_:in:)) Adds an object to the tree corresponding to the specified volume of 3D space. [`- removeElement:withNode:`](/documentation/GameplayKit/GKOctree/remove(_:using:)) Removes the specified object from the tree, using a reference to its containing node. [`- removeElement:`](/documentation/GameplayKit/GKOctree/remove(_:)) Searches for the specified object and removes it from the tree. ### Searching for Elements [`- elementsAtPoint:`](/documentation/GameplayKit/GKOctree/elements(at:)) Returns all objects whose corresponding locations overlap the specified point. [`- elementsInBox:`](/documentation/GameplayKit/GKOctree/elements(in:)) Returns all objects whose corresponding locations overlap the specified volume. ### Constants [`GKBox`](/documentation/GameplayKit/GKBox) The definition of an axis-aligned rectangular bounding volume addressed by the tree. ## Relationships ### Conforms To [`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible) [`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible) [`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol) [`Equatable`](/documentation/Swift/Equatable) [`Hashable`](/documentation/Swift/Hashable) [`CVarArg`](/documentation/Swift/CVarArg) ### Inherits From [`NSObject-swift.class`](/documentation/ObjectiveC/NSObject-swift.class) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)