▁Open Step ▁Foundation Kit . ▁ ▁G E OS ▁Object ive - C ▁The ▁PC ▁G E OS ▁system ▁used ▁a ▁programming ▁language ▁known ▁as ▁G E OS ▁Object ive - C ▁or ▁g oc ; ▁despite ▁the ▁name ▁similarity , ▁the ▁two ▁languages ▁are ▁similar ▁only ▁in ▁overall ▁concept ▁and ▁the ▁use ▁of ▁keywords ▁prefix ed ▁with ▁an ▁@ ▁sign . ▁ ▁Cl ang ▁The ▁Cl ang ▁compiler ▁suite , ▁part ▁of ▁the ▁LL VM ▁project , ▁implements ▁Object ive - C ▁and ▁other ▁languages . ▁After ▁G CC ▁ 4 . 3 ▁( 2 0 0 8 ) ▁switched ▁to ▁G PL v 3 , ▁Apple ▁abandoned ▁it ▁in ▁favor ▁of ▁cl ang , ▁a ▁compiler ▁it ▁has ▁more ▁legal ▁power ▁to ▁modify . ▁As ▁a ▁result , ▁many ▁of ▁the ▁modern ▁Object ive - C ▁language ▁features ▁are ▁supported ▁only ▁by ▁Cl ang . ▁ ▁Apple ' s ▁version ing ▁scheme ▁for ▁its ▁cl ang - based ▁" LL VM ▁compiler " ▁diff ers ▁from ▁the ▁LL VM ' s ▁open - source ▁version ing . ▁See ▁ ▁for ▁a ▁translation ▁ ▁GNU , ▁GNU step , ▁and ▁Win Obj C ▁The ▁GNU ▁project ▁has , ▁for ▁a ▁long ▁time , ▁been ▁interested ▁in ▁a ▁platform ▁to ▁port ▁Ne XT ▁and ▁Ob j - C ▁programs ▁to . ▁The ▁Change Log ▁for ▁the ▁ ▁directory ▁in ▁G CC ▁suggests ▁that ▁it ▁existed ▁before ▁ 1 9 9 8 ▁( G CC ▁ 2 . 9 5 ), ▁and ▁its ▁RE