global_alert_controller.swift

import UIKit

/** Alert controller that can be presented in any context and it will appear on top
*/
class GlobalAlertController: UIAlertController {
    // MARK: - Properties (Private Mutable)

    /** Window to present alert controller in
    */
    private lazy var _window: UIWindow = {
        let window = UIWindow(frame: UIScreen.mainScreen().bounds)

        window.backgroundColor = .clearColor()
        window.rootViewController = UIViewController()

        return window
    }()
    
    // MARK: - Visibility Methods
    
    /** Show the alert controller
    */
    func present(animated: Bool = true, completion: CompletionClosure? = nil) {
        guard let rootVC = _window.rootViewController else { return Errors.report(.ExpectedProperty) }

        _window.makeKeyAndVisible()
        
        rootVC.presentViewController(self, animated: animated, completion: completion)
    }
}