gistfile1.h

// In the header file
@property (retain) NSObject *obj;

// In the code
-(id)init {
    // WRONG: obj = [[NSData alloc] init]; // This won't call [obj retain]; !!!!
    [self setObj:[[NSData alloc] init]]; // CORRECT: [obj retain]; is called properly
    
    return self;
}

-(void)dealloc {
    [obj release];
    
    [super dealloc];
}