problem to understand page 200

[Cretan1986]

In page 200 we have the following code:

Code: (Objective-C)

[_window makeKeyAndVisible]

I really find difficult to understand this code. Page 25 says that the concept is

Code: (Objective-C)

[receiver message]

and as far as I know the receiver must be a class or an instance, but in this case the receiver is an instance variable. What am I missing?

[Cretan1986]

could someone explain this to me?  Thanks in advance 

[stuartjj]

An answer to part of your question:

A receiver can be a method that returns an instance variable.  From page 200:

Code: (Objective-C)

[self.window makeKeyAndVisible];

In this case self.window returns the instance variable _window. 

[afterDark]

I think what is meant here, is that _window is an instance variable of data type <some object>. That is not really a clear sentence, but I mean something along these lines:

in .h file:
@property Rectangle * niceBigRectangle;

in .m file:
@synthesize niceBigRectangle = _niceBigRectangle;

then it is perfectly logical to have somewhere in the methods in the .m file:
[_niceBigRectangle setWidth:10 andHeight:6];

Hope this helps (for the future readers, since Cretan1986 probably moved on as it is so long ago... but this same topic confused me too at first. At least this answer now serves as a memory aid to myself when I have the same question later again)