BaseViewController subclasses are not releasing in swift 3 - ios

Question

I have created BaseViewController to use as subclass for all of my view controllers so that I can show alert whenever I need any progess to show and hide which is lazy variable.
Everything is cool until now. But I figured out that all my viewcontroller which are inherting from this are not releasing. What is the problem?
class BaseViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = UIColor(red: 0.4 / 255.0, green: 100 / 215.0, blue: 120 / 255.0, alpha: 1.0)
}
override var preferredStatusBarStyle: UIStatusBarStyle {
return preferredStatusBarStyle_Internal()
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return supportedInterfaceOrientations_Internal()
}
lazy var progressHUD: MBProgressHUD = {
if let navController = self.navigationController {
return navController.HUD
}
return self.HUD
}()
func showAlert(_ title: String?, message: String) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
let action = UIAlertAction(title: "OK", style: .cancel, handler: { _ in
DispatchQueue.main.async {
self.progressHUD.hide(animated: false, afterDelay: 1.0)
}
})
alert.addAction(action)
present(alert, animated: true, completion: nil)
}
func showPermissionDeniedAlert(_ message: String) {
let alertController = UIAlertController(title: message, message: "Go to Settings?".localized, preferredStyle: .alert)
let settingsAction = UIAlertAction(title: "Settings".localized, style: .default) { _ in
guard let settingsUrl = URL(string: UIApplicationOpenSettingsURLString) else {
return
}
if UIApplication.shared.canOpenURL(settingsUrl) {
if #available(iOS 10.0, *) {
UIApplication.shared.open(settingsUrl, completionHandler: { success in
print("Settings opened: \(success)") // Prints true
})
} else {
let success = UIApplication.shared.openURL(settingsUrl)
print("Settings opened: \(success)")
}
}
}
alertController.addAction(settingsAction)
let cancelAction = UIAlertAction(title: "Cancel", style: .default, handler: nil)
alertController.addAction(cancelAction)
present(alertController, animated: true, completion: nil)
}
}
extension UIViewController {
func preferredStatusBarStyle_Internal() -> UIStatusBarStyle {
return .lightContent
}
func supportedInterfaceOrientations_Internal() -> UIInterfaceOrientationMask {
return isiPad() ? .allButUpsideDown : .all
}
var HUD: MBProgressHUD {
let progressHUD = MBProgressHUD(viewController: self)
return progressHUD
}
}

Answer 1

If the view controller is not releasing it means you are creating retain cycle.
It could be in two places
pass weakself to async block.
DispatchQueue.main.async { [weak self] in
self?.progressHUD.hide(animated: false, afterDelay: 1.0)
}
passing a weak reference if MBProgressHUD init is creating retain cycle
var HUD: MBProgressHUD {
// you can also use weak self
unowned let unownedSelf = self
let progressHUD = MBProgressHUD(viewController: unownedSelf)
return progressHUD
}