AlertController.swift

//
//  ViewController.swift
//  Alert
//
//  Created by Petr Pavlik on 25/03/16.
//  Copyright © 2016 Petr Pavlik. All rights reserved.
//

import UIKit

class AlertController: UIAlertController {
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        if let topView = findTopViewInView(view), let bottomView = findBottomViewInView(view) {
            view.tintColor = .whiteColor()
            colorLabelsInView(topView, toColor: .greenColor())
            bottomView.backgroundColor = UIColor(red:0.910, green:0.286, blue:0.173, alpha: 1)
        }
    }
    
    private func findTopViewInView(view: UIView) -> UIView? {
        if let scrollView = view as? UIScrollView where scrollView.frame.origin.y == 0 {
            return scrollView
        } else if view.subviews.count > 0 {
            for subview in view.subviews {
                if let scrollView = findTopViewInView(subview) {
                    return scrollView
                }
            }
        }
        
        return nil
    }
    
    private func findBottomViewInView(view: UIView) -> UIView? {
        if let scrollView = view as? UIScrollView where scrollView.frame.origin.y > 0 {
            return scrollView
        } else if view.subviews.count > 0 {
            for subview in view.subviews {
                if let scrollView = findBottomViewInView(subview) {
                    return scrollView
                }
            }
        }
        
        return nil
    }
    
    private func colorLabelsInView(view: UIView, toColor: UIColor) {
        
        if let label = view as? UILabel {
            label.textColor = toColor
        }
        
        for subview in view.subviews {
            colorLabelsInView(subview, toColor: toColor)
        }
    }
}

class ViewController: UIViewController {

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        
        let alert = AlertController(title: "Title", message: "Message", preferredStyle: .Alert)
        alert.addAction(UIAlertAction(title: "OK", style: .Cancel, handler: nil))
        presentViewController(alert, animated: true, completion: nil)
    }

}