Add an alertcontroller in a global swift file?

wish helps you You can try setting the selecedIndex property of the UITabBarController.
Your new if statement:

if (viewController is Trove.HomeViewController) {
    let alertController = UIAlertController(title: "Logout", message: "Are you sure you want to log out?", preferredStyle: .Alert)
    let okAction = UIAlertAction(title: "Logout", style: .Default) { (action) in
        tabBarController.selectedIndex = 0 //CHANGE ME
    }
    alertController.addAction(okAction)
    let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel) { (action) in }
    alertController.addAction(cancelAction)
    tabBarController.presentViewController(alertController, animated: true) 
    return false
}

I wish this help you Just now I wrote the code which is provided below. I would like to produce the output for the following code but it crashes when I run it, and it shows nil. , Code for Adding textField in UIALertController :

let alertController = UIAlertController(title: "PlainTextStyle", message: "PlainTextStyle AlertView.", preferredStyle: UIAlertControllerStyle.Alert)
alertController.addTextFieldWithConfigurationHandler { (textField : UITextField) -> Void in
            textField.placeholder = "Login"
        }
let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel) { (result : UIAlertAction) -> Void in
            print("Cancel")
        }
let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default) { (result : UIAlertAction) -> Void in
           print(alertController.textFields?.first?.text)
        }
alertController.addAction(cancelAction)
alertController.addAction(okAction)
self.presentViewController(alertController, animated: true, completion: nil)

 let alertController = UIAlertController(title: "PlainTextStyle", message: "PlainTextStyle AlertView.", preferredStyle: UIAlertControllerStyle.alert)
        alertController.addTextField { (textField : UITextField) -> Void in
            textField.placeholder = "Login"
        }
        let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel) { (result : UIAlertAction) -> Void in
        }
        let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default) { (result : UIAlertAction) -> Void in
        }
        alertController.addAction(cancelAction)
        alertController.addAction(okAction)
        self.present(alertController, animated: true, completion: nil)

Hope that helps Create a new UIViewController, and before presenting it set modalPresentationStyle property to be UIModalPresentationOverCurrentContext. The UIViewController's view must have set clear color as background color and to be overlaid by a UIImageView with alpha 0.5 and has gray color. This will create the semi-transparent effect, then add other UI elements you need (table view, buttons, etc).
Let's say you have CustomViewController for displaying the content above you described. You'll present it using the following statments:

let customVC = CustomViewController()
customVC.modalPresentationStyle = .OverCurrentContext
presentViewController(customVC, animated: false, completion: nil)

Hope this helps I think you will need to create a custom alert controller for this behaviour. I would start by subclassing UIView, then layout your subviews accordingly

Does that help Just store the touch points before UIAlertController Presentation and use that in UIAlterAction because when Alert popover/present while longpress it cannot able to save/get touch point that why touch points inside UIAlterAction is always 0,0.

func longpress(gestureRecognizer: UIGestureRecognizer) {

let touchpointtemp = gestureRecognizer.location(in: self.map_home)

let alert = UIAlertController(title: "New Place", message: "Enter a name", preferredStyle: UIAlertControllerStyle.alert)

    alert.addTextField { (textField: UITextField) in
        textField.placeholder = "Name"
    }

    let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default) { (UIAlertAction) in

        if let tempPlace = alert.textFields?[0].text {
            let place = tempPlace
            let touchpoint = touchpointtemp
            let coordinate = self.map_home.convert(touchpoint, toCoordinateFrom: self.map_home)

            print(coordinate)
            let annotation = MKPointAnnotation()
            let latitude = coordinate.latitude
            let longitude = coordinate.longitude

            annotation.title = place
            annotation.subtitle = "Lat " + (String(format: "%.2f", latitude) + " Lon " + String(format: "%.2f", longitude))
            annotation.coordinate = coordinate
            self.map_home.addAnnotation(annotation)
        }


    }

    let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel) { (UIAlertAction) in

    }


    alert.addAction(okAction)
    alert.addAction(cancelAction)

    present(alert, animated: true, completion: nil)

}