Objective-c dealloc of boolean value

问题

How would I dealloc a boolean value?

Deallocing it this way below gives me a warning: Incompatible pointer to integer conversion assigning to 'BOOL' (aka 'signed char') from 'void *'

- (void)dealloc {
    self.booleanVar = nil;
    [super dealloc];
}

Perhaps I should clarify, this is from a simple class inherited from NSObject.

I'm using the self.var = nil pattern that you see in Cocoa Touch classes. Let's say if it was an NSString* instead should I use self.var = nil or [var release] in the deallocmethod? I'm a little confused here.

回答1:

You don't need to do it. It is not an object. This also explains the warning, as you're trying to assign a nil pointer (that's a NULL for objects basically) to a non-object.

Regarding your second question, yes. You can think of primitive variables as being part of the object, so when it's deallocated the vars will not exist anymore.

But when you have a NSString * in an object, it's just a pointer to another object. If you dealloc the former, the pointer will be deleted, not the NSString. No one might point to it, it's kind of lost in the air, occupying memory. So, before deleting the pointer, if you won't need the object anymore, you send it a release message. That's done in the dealloc method, since it's called to "delete" and object and thus is a good place to delete also every other object that has no use anymore.

回答2:

You dont need to dealloc a BOOL, since BOOLs are really just a byte, which is a primitive data type. You only need to dealloc objects which have been allocated to memory.

回答3:

First of all, if booleanVar is just a plain BOOL value, as in it is declared like so:

BOOL booleanVar;

then you do not need to free up any memory associated with it, since that memory is allocated and freed when the class that holds it is allocated and deallocated. So no code for booleanVar in dealloc will be fine.

However, if you are talking about a pointer for a BOOL, defined like so:

BOOL *booleanVar;

and what you want is to set this variable to a non-value, you should set it equal to NULL instead of nil, since NULL is for value pointers and nil is for object pointers (see: NULL vs nil in Objective-C).

However, if what you want is to free up the memory that the BOOL pointer points to, allocated with malloc or realloc, etc, then try the free() C function (see: http://www.cplusplus.com/reference/clibrary/cstdlib/free/).

What would really clear all this up is if you showed us the property declaration for booleanVar in the class interface, which would tell us exactly what you want to do and you would get an answer with complete certitude.

来源：https://stackoverflow.com/questions/6344162/objective-c-dealloc-of-boolean-value

标签

objective-c

boolean

dealloc