Swift使用AlertController在mapView上添加注释

Question

I'm trying to use an alert controller with a textField to create a mapView annotation using the textField as the title. I can print all the constants I've created but the annotation doesn't work. When I use the annotation code outside the alertAction it works fine, but then I can't get the textField input. What am I doing wrong?

override func viewDidLoad() {
    super.viewDidLoad()

    let uilpgr = UILongPressGestureRecognizer(target: self, action: #selector(ViewController.longpress(gestureRecognizer:)))
    uilpgr.minimumPressDuration = 2
    map.addGestureRecognizer(uilpgr)

}

func longpress(gestureRecognizer: UIGestureRecognizer) {

    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 = gestureRecognizer.location(in: self.map)
            let coordinate = self.map.convert(touchpoint, toCoordinateFrom: self.map)
            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.addAnnotation(annotation)
        }


    }

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

    }


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

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

}

Answer 1

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)

}