▁} ▁- ▁( return _ type ) instance Method ▁{ ▁ ▁// ▁implementation ▁} ▁@ end ▁ ▁Method s ▁are ▁written ▁using ▁their ▁interface ▁declarations . ▁Compar ing ▁Object ive - C ▁and ▁C : ▁ ▁- ▁( int ) method :( int ) i ▁{ ▁ ▁return ▁[ self ▁square _ root : i ]; ▁} ▁ ▁int ▁function ▁( int ▁i ) ▁{ ▁ ▁return ▁square _ root ( i ); ▁} ▁ ▁The ▁syntax ▁allows ▁pseudo - nam ing ▁of ▁arguments . ▁ ▁- ▁( void ) change Color To Red :( float ) red ▁green :( float ) green ▁blue :( float ) blue ▁{ ▁▁▁▁ ▁// ... ▁Im plementation ▁... ▁} ▁ ▁// C alled ▁like ▁so : ▁[ my Color ▁change Color To Red : 5 . 0 ▁green : 2 . 0 ▁blue : 6 . 0 ]; ▁ ▁In ternal ▁representations ▁of ▁a ▁method ▁vary ▁between ▁different ▁implementations ▁of ▁Object ive - C . ▁If ▁my Color ▁is ▁of ▁the ▁class ▁, ▁instance ▁method ▁ ▁might ▁be ▁internally ▁l abeled ▁. ▁The ▁ ▁is ▁to ▁refer ▁to ▁an ▁instance ▁method , ▁with ▁the ▁class ▁and ▁then ▁method ▁names ▁app ended ▁and ▁col ons ▁changed ▁to ▁unders c ores . ▁As ▁the ▁order ▁of ▁parameters ▁is ▁part ▁of ▁the ▁method ▁name , ▁it ▁cannot ▁be ▁changed ▁to ▁suit ▁coding ▁style ▁or ▁expression ▁as ▁with ▁true ▁named ▁parameters . ▁ ▁However , ▁internal ▁names ▁of ▁the ▁function ▁are ▁rarely ▁used ▁directly . ▁Gener ally , ▁messages ▁are