Question

I’m new to iPhone programming, so I might not even be using the correct methods… anyway, I’m trying to make a game, and when I want to create an enemy I make a new UIImageView, like this:

enemyBird *asdf = [[enemyBird alloc] initWithFrame:CGRectMake(30, -20, 45, 30)];
[self.view addSubview:asdf];

When enemyBird initializes, an NSTimer is made so the enemyBird can fly around and do its own thing. Now, I want to get rid of the bird after it leaves the screen, in this code here:

    if (self.center.y > 500)
    {   //[self dealloc];  //doesn't work
        //[self release];  //doesn't work
        //[self removeFromSuperview];   //this makes it disappear, but the NSTimer is still running
    }

But I don’t know how to do that. Am I doing this properly? Or is there an entirely different way I should be doing this? Thanks in advance.

Answer 1

1. As view retains all its subviews you can release your imageView right after you add it to controller’s view:

   enemyBird *asdf = [[enemyBird alloc] initWithFrame:CGRectMake(30, -20, 45, 30)];
   [self.view addSubview:asdf];
   [enemyBird release];
   

2. In your timer handler when bird leaves the screen remove it from superview, set reference to nil (to make sure you won’t access deallocated instance) and invalidate timer so it won’t fire again:

   if (self.center.y > 500)
   {   
       [enemyBird removeFromSuperview];   
       enemyBird = nil;
       [timer invalidate];
   }