num 2 ▁= ▁[ Integer ▁new ]; ▁ ▁int ▁x ; ▁▁ ▁printf (" Enter ▁an ▁integer : ▁"); ▁ ▁scan f ("% d ", ▁& x ); ▁▁ ▁[ num 1 ▁integer : x ]; ▁ ▁[ num 1 ▁show st ars ]; ▁▁ ▁printf (" Enter ▁an ▁integer : ▁"); ▁ ▁scan f ("% d ", ▁& x ); ▁▁ ▁[ num 2 ▁integer : x ]; ▁ ▁[ num 2 ▁show st ars ]; ▁▁ ▁[ num 1 ▁add : num 2 ]; ▁ ▁[ num 1 ▁show int ]; ▁▁ ▁return ▁ 0 ; ▁} ▁ ▁Notes ▁Comp ilation ▁is ▁performed , ▁for ▁example , ▁by : ▁ ▁gcc ▁- x ▁objective - c ▁main . m ▁Integer . m ▁Integer + Ar ithmetic . m ▁Integer + Display . m ▁- lob j c ▁ ▁One ▁can ▁experiment ▁by ▁leaving ▁out ▁the ▁ ▁and ▁ ▁lines ▁and ▁om itting ▁ ▁in ▁compilation . ▁The ▁program ▁will ▁still ▁run . ▁This ▁means ▁that ▁it ▁is ▁possible ▁to ▁mix - and - match ▁added ▁categories ▁if ▁needed ; ▁if ▁a ▁category ▁does ▁not ▁need ▁to ▁have ▁some ▁ability , ▁it ▁can ▁simply ▁not ▁be ▁compile ▁in . ▁ ▁Pos ing ▁Object ive - C ▁perm its ▁a ▁class ▁to ▁wh olly ▁replace ▁another ▁class ▁within ▁a ▁program . ▁The ▁replacing ▁class ▁is ▁said ▁to ▁" pose ▁as " ▁the ▁target ▁class . ▁ ▁Class ▁pos ing ▁was ▁declared ▁deprecated ▁with ▁Mac ▁OS ▁X ▁v 1 0 . 5 , ▁and