Question

I have a problem with the animation. At start, everything is smooth. However, when the application runs for a certain period of time (around 10 min) then the animation lags.

Here is the code in viewDidLoad:

[NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector(updateImage) userInfo:nil repeats:YES];

And in -(void)updateImage: //image fade in

[aSubview release];
[aSubview removeFromSuperview];
aSubview = [[UIImageView alloc] initWithFrame:CGRectMake(28, 64, 265, 284)];
aSubview.image = [slideShowArray objectAtIndex:randNum];
[aSubview setAlpha:0.0];
[UIImageView beginAnimations:NULL context:nil];
[UIImageView setAnimationDuration:2.0];
[aSubview setAlpha:1.0];
[UIImageView commitAnimations];
[self.view addSubview:aSubview];

UIImageView *film = [[UIImageView alloc] initWithFrame:CGRectMake(20, 34, 280, 344)];
film.image = [UIImage imageNamed:@"film5.png"];
[film setAlpha:1.0];
[self.view addSubview:film];
[film release];

Can anyone explain this? Is it due to memory issue or something else? Thanks in advance.

Answer 1

[self.view addSubview:aSubview];

You are adding a subview in every 3 seconds. So after 10 mins there are 200 subviews which requires too much memory and thus slowing the app. Before adding a new subview, remove the previous ones if they are not needed. And if you need 200 subviews simultaneously then you should reconsider your design.

EDIT: After the edit of the question, why do you need to add a film every time? You are adding a new film object every time the method is called. Note that, super view retains subviews. So if the method is called 20 times then you have 20 film objects in memory.