Does copy allocate the required memory?

Here is an example taken from Apple iPhone SDK project:

@interface EADSessionController : NSObject <EAAccessoryDelegate, NSStreamDelegate> {
    EAAccessory *_accessory;
    EASession *_session;
    NSString *_protocolString;

    NSMutableData *_writeData;
    NSMutableData *_readData;
}

...

// initialize the accessory with the protocolString
- (void)setupControllerForAccessory:(EAAccessory *)accessory withProtocolString:(NSString *)protocolString
{
    [_accessory release];
    _accessory = [accessory retain];
    [_protocolString release];
    _protocolString = [protocolString copy];
}

My understanding is that "copy" will also allocate the memory required to copy the protocolString object passed as an 开发者_如何转开发argument, and therefore there is not need to allocate (alloc) something before copying.

Am I right ?

Regards, Apple92

Correct. The copy starts out with a retain count of (at least) one, and you are responsible for eventually releasing it. (See Object Ownership Policy.)