Blocks are a nonstandard extension added by
Apple Inc. to their implementations of the
C,
C++, and
Objective-C programming languages that uses a lambda expression-like syntax to create
closures within these languages. Blocks are supported for programs developed for Mac OS X 10.6+ and iOS 4.0+, although third-party runtimes allow use on Mac OS X 10.5 and iOS 2.2+.