ios - 警报字段关闭一个

Question

我正在构建一个示例 map 应用程序，用户可以在其中放置图钉并使用适当的描述对其进行标记。它接近工作，但描述有一个偏差。也就是说，我放置的第一个图钉将具有默认文本，第二个图钉将具有我为第一个图钉输入的描述，依此类推。

我一直在努力处理这段代码，我意识到还有其他问题。一旦我让它工作，我将把它放在代码审查中，但请随时指出任何其他错误。

我已经突出显示了相关方法，但在 ViewController 中包含了所有内容。

import UIKit
import MapKit
import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate {

    var locationManager = CLLocationManager()
    var location: CLLocation!
    var newAnnotation: String?

    @IBOutlet weak var map: MKMapView!

    @IBAction func refreshMap(sender: AnyObject) {
        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.startUpdatingLocation()
        location = locationManager.location
        locationManager.stopUpdatingLocation() //not my question right now but I'm pretty sure this is dumb
        let center = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
        let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01))

        self.map.setRegion(region, animated: true)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        refreshMap(self.map)
        let uilpgr = UILongPressGestureRecognizer(target: self, action: "addPlace:")
        uilpgr.minimumPressDuration = 1
        map.addGestureRecognizer(uilpgr)
    }

    //this is the method in question
    func addPlace(gestureRecognizer:UIGestureRecognizer) {
        if gestureRecognizer.state == UIGestureRecognizerState.Began {
            let touchPoint = gestureRecognizer.locationInView(self.map)
            let newCoordinate: CLLocationCoordinate2D = map.convertPoint(touchPoint, toCoordinateFromView: self.map)
            let annotation = MKPointAnnotation()
            annotation.coordinate = newCoordinate
            let alert = UIAlertController(title: "New Memorable Place", message: "Enter a description for this location", preferredStyle: .Alert)

            alert.addTextFieldWithConfigurationHandler({ (textField) -> Void in
                textField.text = "Description"
            })

            alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { (action) -> Void in
                self.newAnnotation = alert.textFields![0].text
            }))

            self.presentViewController(alert, animated: true, completion: nil)

            annotation.title = newAnnotation
            map.addAnnotation(annotation)
            }
        }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        let location = locations.last! as CLLocation

        let center = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
        let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01))

        self.map.setRegion(region, animated: true)
    }

}

Answer 1

您应该将 AddPlace 方法的最后两行(将注释添加到 map 中)移动到警报的操作处理程序中。操作处理程序将在将来的某个时间异步调用。