How to release subviews

Question

In my iPhone/iPad app,

I am adding one subview to my main view.

This subview has one imageview and button.

When to release them ?

My code is here,

 customAlertView=[[UIView alloc] initWithFrame:CGRectMake(0, 0, 600, 600)];


         UIImageView *imgv=[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"celebration.png"]];

          UIButton *btnOK=[UIButton buttonWithType:UIButtonTypeCustom];

         [btnOK setTitle:@"OK" forState:UIControlStateNormal];
         [btnOK addTarget:self action:@selector(alertOKClicked) forControlEvents:UIControlEventTouchUpInside];

         [customAlertView addSubview:btnOK];
         [customAlertView addSubview:imgv];
         [self.view addSubview:customAlertView];

         [imgv release];
         [btnOK release];



In one another method I am writing the code.

  [customAlertView removeFromSuperview];

My confusion is imageview and button is there If

1. I release the customalertview here will it releases its subviews automatically. If yes then no problem.

2. If NO how to release it

   as I have done here released the objects immediately after adding subviews. It will cause my OK button Unworthy. And will not affect the button click.

   So, On removing from superview should I write.

[[customalertview subviews] release];

Answer 1

Your code is correct.

You release them after you've added them to the alert view, as the alert view takes care of retaining them. When you call removeFromSuperview, it'll get released automatically.

Answer 2

I think the points you are missing, based on your comments on the existing answers, are the following:

• A view retains its subviews - so if you create a new view object, and add it as a subview to something else, you can then safely release it, unless you'd like to keep a reference around for it yourself.
• When a view is removed from its superview, it is released. So if there are no more objects retaining it, it will be deallocated.
• When a view is deallocated, it will automatically release all of its subviews, and so on down the tree.

Enable ARC as soon as you are able to.

Answer 3

You are doing it the right way. The customalertview will releases its subviews automatically.

Your object will be released when the release count go to 0, that means in the theory, and if you are coding well, that this object does not have any reference to it anymore.

While you maintain your custom alertView in your view, you have an object retaining your things, so the release count will not be 0 until you remove the customAlertView, because you have added they to the customAlertView, and when you remove the alert, the alert will be released, and all the things that it is retaining will be released too.

Hope it help you to understand how things work.

If you want to know more about memory management you can take a look at apple documentation here

EDIT:

I forgot to mention that you will need to release your custom alert too after you remove it.

If you do not understand the memory management you also can take a look at: http://cocoadevcentral.com/d/learn_objectivec/ section 7