/ C ++ . ▁ ▁Return ▁types ▁can ▁be ▁any ▁standard ▁C ▁type , ▁a ▁pointer ▁to ▁a ▁generic ▁Object ive - C ▁object , ▁a ▁pointer ▁to ▁a ▁specific ▁type ▁of ▁object ▁such ▁as ▁NS Array ▁* , ▁NS Image ▁* , ▁or ▁NSString ▁* , ▁or ▁a ▁pointer ▁to ▁the ▁class ▁to ▁which ▁the ▁method ▁belongs ▁( inst anc et ype ). ▁The ▁default ▁return ▁type ▁is ▁the ▁generic ▁Object ive - C ▁type ▁. ▁ ▁Method ▁arguments ▁begin ▁with ▁a ▁name ▁label ing ▁the ▁argument ▁that ▁is ▁part ▁of ▁the ▁method ▁name , ▁followed ▁by ▁a ▁colon ▁followed ▁by ▁the ▁expected ▁argument ▁type ▁in ▁parentheses ▁and ▁the ▁argument ▁name . ▁The ▁label ▁can ▁be ▁omitted . ▁ ▁- ▁( void ) set Range Start :( int ) start ▁end :( int ) end ; ▁- ▁( void ) import Document With Name :( NSString ▁*) name ▁with Spec ified Preferences : ▁( Preferences ▁*) p refs ▁before Page :( int ) insert Page ; ▁ ▁A ▁derivative ▁of ▁the ▁interface ▁definition ▁is ▁the ▁category , ▁which ▁allows ▁one ▁to ▁add ▁methods ▁to ▁existing ▁classes . ▁ ▁Im plementation ▁The ▁interface ▁only ▁decl ares ▁the ▁class ▁interface ▁and ▁not ▁the ▁methods ▁themselves : ▁the ▁actual ▁code ▁is ▁written ▁in ▁the ▁implementation ▁file . ▁Im plementation ▁( method ) ▁files ▁normally ▁have ▁the ▁file ▁extension ▁. m , ▁which ▁originally ▁sign ified ▁" messages ". ▁ ▁@ implementation ▁class name ▁+ ▁( return _ type ) class Method ▁{ ▁ ▁// ▁implementation