How to change the background color of the UIAlertController?

Question

Due to strange behavior of UIActionSheet in iOS 8, I have implemented UIAlertController with UIAction as buttons in it. I would like to change the entire background of the U

Answer 1

Here is a UIAlertController extension that works on both iPad and iPhone. Cancel button will change from a dark colour to white automatically depending on what blurStyle is selected:

extension UIAlertController {

    private struct AssociatedKeys {
        static var blurStyleKey = "UIAlertController.blurStyleKey"
    }

    public var blurStyle: UIBlurEffectStyle {
        get {
            return objc_getAssociatedObject(self, &AssociatedKeys.blurStyleKey) as? UIBlurEffectStyle ?? .extraLight
        } set (style) {
            objc_setAssociatedObject(self, &AssociatedKeys.blurStyleKey, style, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)

            view.setNeedsLayout()
            view.layoutIfNeeded()
        }
    }

    public var cancelButtonColor: UIColor? {
        return blurStyle == .dark ? UIColor(red: 28.0/255.0, green: 28.0/255.0, blue: 28.0/255.0, alpha: 1.0) : nil
    }

    private var visualEffectView: UIVisualEffectView? {
        if let presentationController = presentationController, presentationController.responds(to: Selector(("popoverView"))), let view = presentationController.value(forKey: "popoverView") as? UIView // We're on an iPad and visual effect view is in a different place.
        {
            return view.recursiveSubviews.flatMap({$0 as? UIVisualEffectView}).first
        }

        return view.recursiveSubviews.flatMap({$0 as? UIVisualEffectView}).first
    }

    private var cancelActionView: UIView? {
        return view.recursiveSubviews.flatMap({
            $0 as? UILabel}
        ).first(where: {
            $0.text == actions.first(where: { $0.style == .cancel })?.title
        })?.superview?.superview
    }

    public convenience init(title: String?, message: String?, preferredStyle: UIAlertControllerStyle, blurStyle: UIBlurEffectStyle) {
        self.init(title: title, message: message, preferredStyle: preferredStyle)
        self.blurStyle = blurStyle
    }

    open override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()

        visualEffectView?.effect = UIBlurEffect(style: blurStyle)
        cancelActionView?.backgroundColor = cancelButtonColor
    }
}

The following UIView extension is also needed:

extension UIView {

    var recursiveSubviews: [UIView] {
        var subviews = self.subviews.flatMap({$0})
        subviews.forEach { subviews.append(contentsOf: $0.recursiveSubviews) }
        return subviews
    }
}

Example:

let controller = UIAlertController(title: "Dark Alert Controller", message: nil, preferredStyle: .actionSheet, blurStyle: .dark)

// Setup controller actions etc...

present(controller, animated: true, completion: nil)

iPhone:

iPad: