objective c - Why do functions use -(void) and not -(nil) in Obj-C? -

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Objective- I often see functions that do not declare anything: 

  - (zero) myFunction {single ?? |   
 but why  zero , this way  
  - (zero) myFunction {a ?? |   
 They both do not return "nothing"?  
 
 Historically in the related languages ​​(syntax) as the language of C-language,  Zero  indicates that no type is being returned from the function.  
 More precise, in the form of variables (or related to it) given  type , there are also types in functions, for example, a function that returns an integer A  int  type function or a function whose  int  is the same even if it gives something else.  
 If the function does not return anything - it does not return anything - how is it related? It does not have any type, and  zero  type represents such a thing.  
 I do not know in Objective-C, but if I correctly understand, like the zero   id (or any type of ID), almost like an underlying implementation.  
 and  faucet  is a (zero *) type, later an  typeless  indicator can indicate anything, as if it were in C And C ++  
 Any such function which gives zero, it will mean that it is any type of ID, it is also not known that it also makes sense. So then and there, there is a type (any type?) Before  (zero) myfunction  is a type  (zero) myFunction  also no.  
 In addition to this, zero is an inherent constant; Returning Nile is like saying that your function returns a specific number for example ( (1) myFunction ). It will not make any sense, is not it?

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