Model I/O uses zones to ensure that related allocations—such as the multiple vertex and index buffers associated with a MDLMesh object—use contiguous blocks of memory for optimal performance. When working with a MDLMeshBufferAllocator object that does not implement its own zone management, Model I/O uses this zone class.This class declares no methods or properties of its own. For the key functionality of all mesh buffer zone objects, see MDLMeshBufferZone.
A MDLVertexBufferLayout object describes layout information for a vertex buffer in a MDLMesh object. A collection of vertex layer objects, vertex attribute objects, and additional information forms a MDLVertexDescriptor object, which completely describes the layout of vertex buffers for a mesh.