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Removing views from a UIStackView with removeArrangedSubview()

That was a long chapter, and I hope you learned a lot. But you deserve a break, so I have some good news: it's trivial to remove views from a UIStackView. Heck, at its simplest it's just a matter of telling removeArrangedSubview() which view you don’t want then removing that view from its superview – the others are automatically resized and re-arranged to fill the space.

However, using removeArrangedSubview() doesn’t remove the view altogether – it keeps the view in memory, which is helpful if you plan to re-add it later on because you can avoid recreating it. Here, though, we actually want to remove the web view and destroy it entirely, and that can be done with a call to removeFromSuperview() instead.

In this particular project, we need to do a little more:

We want the delete button to work only if there's a web view selected.
We want to find the location of the active web view inside the stack view, then remove it.
If there are now no more web views, we want to call setDefaultTitle() to reset the user interface.
We need to find whatever web view immediately follows the one that was removed.
We then make that the new selected web view, highlighting it in blue.

We already pointed the delete button at a method called deleteWebView(), so all you need to do is plug this in. I've added comments to make sure it's all clear:

@objc func deleteWebView() {
    // safely unwrap our webview
    if let webView = activeWebView {
        if let index = stackView.arrangedSubviews.firstIndex(of: webView) {
            // We found the webview – remove it from the stack view and destroy it
            webView.removeFromSuperview()

            if stackView.arrangedSubviews.count == 0 {
                // go back to our default UI
                setDefaultTitle()
            } else {
                // convert the Index value into an integer
                var currentIndex = Int(index)

                // if that was the last web view in the stack, go back one
                if currentIndex == stackView.arrangedSubviews.count {
                    currentIndex = stackView.arrangedSubviews.count - 1
                }

                // find the web view at the new index and select it
                if let newSelectedWebView = stackView.arrangedSubviews[currentIndex] as? WKWebView {
                    selectWebView(newSelectedWebView)
                }
            }
        }
    }
}

So, although the act of removing a view from a UIStackView is just a matter of calling either removeArrangedSubview() or removeFromSuperview() depending on whether you want to use it again, we need to do a little more to make sure the user interface updates correctly.

The last thing we're going to do is talk about multitasking on iPad, and add a few user interface clean ups to make the project complete…