Drag copy between UIViews

I am essentially trying to do what is covered in this question, but copy instead of move.

Here is what the view hierarchy looks like (copied from the existing question). A and B are both inside a common superview. X is a view inside A.

  A        B
_____    _____
|   |    |   |
| X | -> |   |
|___|    |___|

I want to copy X into B. A is a list of available items. I want to choose an item from A and add a copy of it to B.

This is what I have come up with so far. After detecting a touch in X, I make a copy of the view (viewCopy). Then I add viewCopy to A and add the original开发者_StackOverflow社区 view to the superview of A and B. This is because the touches are probably active on the original view and not on the copied view. I want the new (copied) view to respond to drag for a smooth transition from A to B.

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{        
    id viewCopy = [self mutableCopy];
    [self.superview.superview addSubview:self];
    [self.superview addSubview:viewCopy];
    [viewCopy release];
}

This obviously does not work. It is a very crude try, but I am not sure how to go about doing this. Any help would be great. Thanks.

---

UIView doesn’t adhere to the NSCopying protocol, so attempting to copy it is likely failing—it’s hitting the base NSObject -mutableCopy, which doesn’t do what you want. To get your clone view, you’ll have to recreate it. Easiest way to handle that is to either set up your X view so it can load from a XIB or implement it as a custom UIView subclass that can set up its own contents.

For an example of the former, check out the docs; the example is for loading custom table view cells, but the technique’s easily applicable to a generic custom view.