removeFromSuperview releases subviews?

[Shubo]

When you remove a view from its superview using "removeFromSuperview" does it remove the view's subview as well or do you have to remove the subviews yourself before removing the view from its superview?

Thanks.

[Not_Appy_At_All]

Originally Posted by Shubo

When you remove a view from its superview using "removeFromSuperview" does it remove the view's subview as well or do you have to remove the subviews yourself before removing the view from its superview?

Thanks.

If you have a view, that has subviews, from my experience removing just the View also removes the subviews.

With questions like these, I usually create a simple program isolating the problem and try different things to see what the outcome is.

[Shubo]

Thanks. That's what I thought but my app is getting bigger slightly over a time so I was wondering the subviews weren't being released.

[Duncan C]

Originally Posted by Shubo

When you remove a view from its superview using "removeFromSuperview" does it remove the view's subview as well or do you have to remove the subviews yourself before removing the view from its superview?

Thanks.

The answer is "it depends."

The view you remove from it's superview won't remove ITs views, but it might release them. Here's how it works.

If you remove a view from it's superview, the superview sends the newly removed view a release message. If that causes it's retain count to drop to zero, it gets deallocated. When a view is deallocated, it releases it's subviews also.

If you want to have a view (and all it's subviews) get deallocated when you remove it from it from it's superview, make sure the only object retaining it is it's superview. Then, when you remove it, the whole ball of wax gets deallocated.

If you want the view and it's subviews to stick around so you can use it somewhere else, have your view controller save it in a retained property.

This is a very common design pattern in Cocoa. You have some object that serves as a container for other objects. (views, arrays, dictionaries, sets, and custom data container objects, and even complex groups like an array of dictionaries of arrays of objects) Only the container object retains the things it contains. When you release the container object, everything "inside" the container gets released.

[Shubo]

Thank for clarifying. I see a possible problem. I am retaining the view so even though I remove it from its superview it and its subviews might not get released.

Originally Posted by Duncan C

The answer is "it depends."

The view you remove from it's superview won't remove ITs views, but it might release them. Here's how it works.

If you remove a view from it's superview, the superview sends the newly removed view a release message. If that causes it's retain count to drop to zero, it gets deallocated. When a view is deallocated, it releases it's subviews also.

If you want to have a view (and all it's subviews) get deallocated when you remove it from it from it's superview, make sure the only object retaining it is it's superview. Then, when you remove it, the whole ball of wax gets deallocated.

If you want the view and it's subviews to stick around so you can use it somewhere else, have your view controller save it in a retained property.

This is a very common design pattern in Cocoa. You have some object that serves as a container for other objects. (views, arrays, dictionaries, sets, and custom data container objects, and even complex groups like an array of dictionaries of arrays of objects) Only the container object retains the things it contains. When you release the container object, everything "inside" the container gets released.

[Not_Appy_At_All]

Originally Posted by Shubo

Thank for clarifying. I see a possible problem. I am retaining the view so even though I remove it from its superview it and its subviews might not get released.

I never retain any view or its subviews.

I remove them and reinitialize them when I need them...

I think the term is "Lazy Loading"?

I also release the View and all its subviews as soon as I create them...

So when I remove the view from superview, it removes all of it...

But Duncan's post makes me think I need to do some more reading and playing around under the hood...