block in Objective-C

also known as closures or lambdas

block syntax:
1. ^
2. ( parameterType parameterName )
3. { code to be executed }


ex:
// declare a block variable test
void (^test)(void);
//  define block's code
test = ^ { NSLog("test"); };
// execute block
test();

ex:
void (^test)(void) = ^ { NSLog("test"); };