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

The best decision that i found (without white spots on the sides)

Link to original answer by Vadim Akhmerov

Answer:

It is easier to subclass UIAlertController.

The idea is to traverse through view hierarchy each time viewDidLayoutSubviews gets called, remove effect for UIVisualEffectView's and update their backgroundColor:

class AlertController: UIAlertController {

    /// Buttons background color.
    var buttonBackgroundColor: UIColor = .darkGray {
        didSet {
            // Invalidate current colors on change.
            view.setNeedsLayout()
        }
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        // Traverse view hierarchy.
        view.allViews.forEach {
            // If there was any non-clear background color, update to custom background.
            if let color = $0.backgroundColor, color != .clear {
                $0.backgroundColor = buttonBackgroundColor
            }
            // If view is UIVisualEffectView, remove it's effect and customise color.
            if let visualEffectView = $0 as? UIVisualEffectView {
                visualEffectView.effect = nil
                visualEffectView.backgroundColor = buttonBackgroundColor
            }
        }

        // Update background color of popoverPresentationController (for iPads).
        popoverPresentationController?.backgroundColor = buttonBackgroundColor
    }

}


extension UIView {

    /// All child subviews in view hierarchy plus self.
    fileprivate var allViews: [UIView] {
        var views = [self]
        subviews.forEach {
            views.append(contentsOf: $0.allViews)
        }

        return views
    }

}

Usage:

1. Create alert controller(use now AlertController instead UIAlertController)

let testAlertController = AlertController(title: nil, message: nil, preferredStyle: .actionSheet)

2. Set background color on custom class "AlertController":

var buttonBackgroundColor: UIColor = .darkGray