Hi, Please give me some suggestions about how to change a NSString variable.

At my class, I set a member var:

NSString *m_movieName;
...
@property(nonatomic, retain) NSString *m_movieName;

At viewDidLoad method, I assign a default name to this var:

-(void)viewDidLoad{
NSString *s1 = [[NSString alloc] initWithFormat:@"Forrest Gump"];
self.m_movieName = s1;
...
[s1 release];
[super viewDidLoad]
}

At some function, I want to give a new name to this var, so I did like:

-(void)SomeFunc{
NSString *s2 = [[NSString alloc] initWithFormat:@"Brave Heart"];
//[self.movieName release]; // ??????? Should perform here?
self.m_moiveName = s2;
[s2 release];
}

I know, NSString* var is just a pointer to an allocated memory block, and 'assign' operation will increment this memory block's using count. For my situation, should I release m_movieName before assigning a value to it? If I do not release it (via [self.movieName release]), when and where will the previous block be released? Thanks for your help very much!