How to explain this Objective C method declaration "- method:parameter;"

Question

Declaring, implementing and using method like this:

Test.h:

- method:parameter;

Test.m:

- method:parameter{ return nil; }

Using:

[test method:anObject];

There is no return-type and parameter-type, but it works without any warning or error. Can somebody explain it?

@ViTo Brothers Apoyan, actually no, it's id if it's unspecified. — Dan Rosenstark
– Dan Rosenstark, Commented Jun 9, 2011 at 6:23

user557219 · Accepted Answer · 2011-06-09 06:11:59Z

If a return or parameter type isn’t explicitly declared, it’s assumed to be the default type for methods and messages — an id.

So:

- method:parameter;

effectively means:

- (id)method:(id)parameter;

and, correspondingly:

- method:parameter{ return nil; }

effectively means:

- (id)method:(id)parameter{ return nil; }

John Calsbeek · Accepted Answer · 2011-06-09 06:13:52Z

If a return or parameter type isn’t explicitly declared, it’s assumed to be the default type for methods and messages—an id.

taskinoor · Accepted Answer · 2011-06-09 06:13:49Z

3

Default type in Obj-C is id. So here the both the return and parameter is id.

answered Jun 9, 2011 at 6:13

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3 Answers 3