Object Runtime Get low-level support for basic Objective-C features, Cocoa design patterns, and Swift integration. TopicsObject BasicsNSObjectNSObjectProtocolNSKeyValueCodingCopyingNSCopyingNSMutableCopyingValue Wrappers and TransformationsNSNumberNSValueValueTransformerSwift SupportReferenceConvertibleClasses Bridged to Swift Standard Library Value TypesRemote ObjectsNSProxyMemory ManagementMemory Management FunctionsObjective-C RuntimeObjective-C Runtime UtilitiesVersions and API AvailabilityFoundation Framework Version NumbersLegacyDistributed Objects SupportObjective-C Garbage Collection See AlsoLow-Level UtilitiesXPCProcesses and ThreadsStreams, Sockets, and Ports