Confused about alloc and release

I'm a little confused about Objective-C and allocating/releasing objects.

If I do this:

NSString *myString;开发者_运维知识库

if([someString isEqualToString: @"test1"]){
    myString = @"got 1";
}else{
    myString = @"got 2";
}

Do I have to release myString after that?

And the same with self-defined objects:

myOwnObject *someObject = [someArray objectAtIndex: 1];

myButton.label1.text = someObject.name;

Do I have to release someObject?

The reason why I'm asking is that I get memory-leaks in a method and I can't find where it is. So I'm trying to figure out whether I do the alloc/release stuff correctly. The leak occurs on a NSPlaceholderString (I guess that's somewhere hidden in my NIB-File).

Also - if I have an object, allocate it, but only use some of the properties, but DO a release of every property on dealloc - will this cause memory leaks?

Sorry - hope my questions do make at least some sense :)

Thanks for any help!

Listen to me. THIS IS THE ONLY RULE THAT MATTERS.

If you use a method with "copy", "alloc", "new", or "retain" in the name

You own the object and MUST later release or autorelease it.

If you don't:

Don't!

But don't expect the object to stick around outside of that scope, because you don't own it.

It's that simple.

MyClass *foo = [[MyClass alloc] init];
[array addObject:foo];
[foo release];

Did you use "copy", "retain", "new", or "alloc"? Yes. Release it.

MyClass *someObject = [someArray objectAtIndex:0];

Did you use "copy", "retain", "new", or "alloc"? No. Don't release it.

BUT

If you have an instance variable which you need to access in other methods:

ivar = [[someArray objectAtIndex:0] retain];

Then you're guaranteed it will stick around because you own it.

(Another way to handle this is with @property (retain) properties, because then you can do self.ivar = someObject and it'll retain it for you.)

But remember to release them in -dealloc!

No, you don't have to release either of those. I usually release only objects that I alloc, such as this snippet:

NSString *string = [[NSString alloc] initWithFormat:@"%@", something];
// yadda yadda yadda some code...
[string release];

To answer your first question, you don't need to release strings created with the @"" syntax.

On your second example, you should not have to release someObject. However, a problem could arise if your dealloc method in your myOwnObject class does not correctly release all of its instance variables.