Re: checking if an object's instance exists.
Re: checking if an object's instance exists.
- Subject: Re: checking if an object's instance exists.
- From: Kevin Ballard <email@hidden>
- Date: Sat, 5 Feb 2005 01:11:25 -0500
When you release object1, set it to nil afterwards. Just releasing it
won't set it to nil, so if it's the last reference you'll end up with a
pointer to random memory, which could crash or it could raise an
exception (depending on if any of the memory has been re-used for
anything else). If you set object1 to nil after releasing it, you can
now check the pointer to see if it's nil or not (which is what you're
doing), and if it's nil then you know you've already released it.
You should also set object1 to nil in your init method to be safe
(AFAIK there's no docs saying ivars are zeroed when allocated, so I
wouldn't assume it)
On Feb 5, 2005, at 12:45 AM, Aaron Boothello wrote:
I've subclasses NSObject for a custom class by the name of 'myObject'.
An instance of 'myObject' is called 'object1'.
I allocate memory and initialize the instance like this:
object1 = [[myObject alloc]init];
And release it like this:
[object1 release];
At one point in my code, i need to access the instance, but it could
happen that the object hasnt been allocated or initialized. how do i
check ?
my block of code looks something liek this:
-(void)method1
{
[release object1];
[self method2];
}
-(void)method2
{
int x;
if(object1)
x=[object1 length];
}
but it dosent seem to work.
basically i need to check if the instance object1 exists or not.
Any suggestions ?
--
Kevin Ballard
email@hidden
http://www.tildesoft.com
http://kevin.sb.org
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