Question

As I have seen in many examples, first they allocate memory for the temporary object and later the same object is assigned to self. For example, I have a code snippet here :

-(void)viewDidLoad {
   [super viewDidLoad];
   Movie *newMovie = [[[Movie alloc] initWithTitle:@"Iron Man"
                                    boxOfficeGross:[NSNumber numberWithFloat:650000000.00] 
                                           summary:@"Smart guy makes cool armor"] autorelease];
   self.movie = newMovie;
 }

Why cant we perform like:

self.movie =[[[Movie alloc] initWithTitle:@"Iron Man"
                           boxOfficeGross:[NSNumber numberWithFloat:650000000.00]
                                  summary:@"Smart guy makes cool armor"] autorelease];

Answer 1

Both are essentially the same. They adhere to the ownership clause – You release what create/retain. The difference, though not so obvious here, is that the time it takes for an autoreleased object to be released. Say, if loads of such autoreleased objects lingered around in the memory, this could create memory problems. If we released them and their retain count is zero, they are immediately deallocated and memory is freed up.