NSValue is a wrapper class for C data types, and NSNumber is a wrapper class for C number data types such as int, double, and float.
An associative data container of key-value pairs with unique keys.
Searching and element addition and removal (in the case of NSMutableDictionary) is faster-than-linear.
Classes that store times and dates and represent calendrical information.
Beginning as the successor to OPENSTEP/Mach, this framework has deviated from OpenStep compliance, and is in some places incompatible.
The Foundation Kit is implemented in GNUstep's Base Package (libs-base).
SwiftFoundation (swift-corelibs-foundation) is Apple's open-source Swift implementation of the Foundation API for platforms where there is no Objective-C runtime.