What is the preferred and/or correct way to release an NSMutableString (or any other class for that matter) instance and assign a new instance to the same variable in Objective-C on the iPhone?

Currently I'm using

[current release];
current = [NSMutableString new];

but I understand that the following works, too.

NSMutableString *new = [NSMutableString new];
[current release];
current = [new retain];
[new release];

The variable current is declared in the interface definition of my class and gets released in dealloc.