AlertViewController

AlertViewController is UIAlerController subclass. It adds ability to display UIImage above the title label. Functionality is achieved by adding \n characters to title, to make space for UIImageView that is added as subview to UIAlertController.view. Set title as normal but when retrieving value use originalTitle property. It is a bit of a hack, yes. But works on iOS 9, 10 and latest iOS 11 (beta 5). I find it easier to maintain than trying to implemnet class that mimics behaviour of UIAlertController from scratch. Get is on GitHub.

import UIKit

/// Adds ability to display `UIImage` above the title label of `UIAlertController`.
/// Functionality is achieved by adding “\n” characters to `title`, to make space
/// for `UIImageView` to be added to `UIAlertController.view`. Set `title` as
/// normal but when retrieving value use `originalTitle` property.
class AlertController: UIAlertController {
    /// - Return: value that was set on `title`
    private(set) var originalTitle: String?
    private var spaceAdjustedTitle: String = ""
    private weak var imageView: UIImageView? = nil
    private var previousImgViewSize: CGSize = .zero
    
    override var title: String? {
        didSet {
            // Keep track of original title
            if title != spaceAdjustedTitle {
                originalTitle = title
            }
        }
    }
    
    /// - parameter image: `UIImage` to be displayed about title label
    func setTitleImage(_ image: UIImage?) {
        guard let imageView = self.imageView else {
            let imageView = UIImageView(image: image)
            self.view.addSubview(imageView)
            self.imageView = imageView
            return
        }
        imageView.image = image
    }
    
    // MARK: -  Layout code
    
    override func viewDidLayoutSubviews() {
        guard let imageView = imageView else {
            super.viewDidLayoutSubviews()
            return
        }
        // Adjust title if image size has changed
        if previousImgViewSize != imageView.bounds.size {
            previousImgViewSize = imageView.bounds.size
            adjustTitle(for: imageView)
        }
        // Position `imageView`
        let linesCount = newLinesCount(for: imageView)
        let padding = Constants.padding(for: preferredStyle)
        imageView.center.x = view.bounds.width / 2.0
        imageView.center.y = padding + linesCount * lineHeight / 2.0
        super.viewDidLayoutSubviews()
    }
    
    /// Adds appropriate number of "\n" to `title` text to make space for `imageView`
    private func adjustTitle(for imageView: UIImageView) {
        let linesCount = Int(newLinesCount(for: imageView))
        let lines = (0..<linesCount).map({ _ in "\n" }).reduce("", +)
        spaceAdjustedTitle = lines + (originalTitle ?? "")
        title = spaceAdjustedTitle
    }
    
    /// - Return: Number new line chars needed to make enough space for `imageView`
    private func newLinesCount(for imageView: UIImageView) -> CGFloat {
        return ceil(imageView.bounds.height / lineHeight)
    }
    
    /// Calculated based on system font line height
    private lazy var lineHeight: CGFloat = {
        let style: UIFontTextStyle = self.preferredStyle == .alert ? .headline : .callout
        return UIFont.preferredFont(forTextStyle: style).pointSize
    }()
    
    struct Constants {
        static var paddingAlert: CGFloat = 22
        static var paddingSheet: CGFloat = 11
        static func padding(for style: UIAlertControllerStyle) -> CGFloat {
            return style == .alert ? Constants.paddingAlert : Constants.paddingSheet
        }
    }
}

UIAlertAction+Extensions

Adds ability to display image left of the action title, by leveraging KVC.Also checks whether UIAlertAction responds to appropriate selector to avoid crashes if property is not available in the future.

import UIKit
/// Adds ability to display image left of the action title, by leveraging KVC. 
/// Also checks whether `UIAlertAction` responds to appropriate selector to 
/// avoid crashes if property is not available in the future.
extension UIAlertAction {
    
    /// Image to display left of the action title
    var actionImage: UIImage? {
        get {
            if self.responds(to: Selector(Constants.imageKey)) {
                return self.value(forKey: Constants.imageKey) as? UIImage
            }
            return nil
        }
        set {
            if self.responds(to: Selector(Constants.imageKey)) {
                self.setValue(newValue, forKey: Constants.imageKey)
            }
        }
    }
    
    private struct Constants {
        static var imageKey = "image"
    }
}