Present UIAlertView from current modal's delegate - swift

Question

The issue in question involves an AddItemView which is presented modally by its delegate and contains a tableView. When the user selects an item from the tableView, it triggers an action on the delegate. Depending on the response from the server, the delegate may present a either another modal view or a UIAlertView on top of the current modal.
Important Note: This UIAlertView needs to be presented while the modal is still on screen. The modally presented view containing the tableView cannot be dismissed after user selection because the user needs to be able to select multiple items from the table and, one by one, send them back to the delegate for processing.
Currently, the UIAlerView is not being displayed and I suspect it is because the already-presented modal is preventing that. Is there a workaround to present the UIAlertView from the delegate when the delegate is sitting underneath a modal and without dismissing that modal?
The UIAlertView is currently displayed like so by the delegate, while the delegate is sitting under a modal:
var alert = UIAlertController(title: "Error", message: "Error message from server", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "actionOne", style: .Default, handler: { action in
// perform some action
}))
alert.addAction(UIAlertAction(title: "actionTwo", style: .Destructive, handler: { action in
// perform some action
}))
self.presentViewController(alert, animated: true, completion: nil)
Here is the error that is returned when the UIAlertView is presented by the delegate:
Warning: Attempt to present <UIAlertController: 0x156da6300> on <productionLINK_Scanner.ContainerContents: 0x156e65b20> whose view is not in the window hierarchy!
If possible, please provide answer using Swift.

Answer 1

Solved:
Used the following extension, thanks to yonat on GitHub:
extension UIApplication {
class func topViewController(base: UIViewController? = UIApplication.sharedApplication().keyWindow?.rootViewController) -> UIViewController? {
if let nav = base as? UINavigationController {
return topViewController(base: nav.visibleViewController)
}
if let tab = base as? UITabBarController {
if let selected = tab.selectedViewController {
return topViewController(base: selected)
}
}
if let presented = base?.presentedViewController {
return topViewController(base: presented)
}
return base
}
}
Within the delegate in question, it was implemented like so:
var alert = UIAlertController(title: "Alert Title", message: "Message Body", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { action in
}))
if let topController = UIApplication.topViewController(base: self) {
topController.presentViewController(alert, animated: true, completion: nil)
} else {
// If all else fails, attempt to present the alert from this controller.
self.presentViewController(alert, animated: true, completion: nil)
}
This now allows the following process:
ContainerView is loaded as a delegate of ItemTableView
User clicks searchButton
ContainerView modally presents a list of items ItemTableView
Each time a use selects a row in ItemTableView, the didSelectItem function is called in the instance of ContainerView that presented the ItemTableView. The ItemTableView does NOT get dismissed - the user can continue selecting items.
ContainerView submits a request to the server
Depending on the response, the ContainerView may present a UIAlertView.
The alertView is properly displayed using the above-mention code on top of whatever view is top-most in the hierarchy.

Answer 2

"When the user selects an item, it triggers and action on the delegate"
set a break point at start of the delegate method which is triggered by selecting an item. check whether that delegate method is being called or not ?
and test this too. (ACTION :UIAlertAction!)in