按下按钮时的当前位置图引脚

Question

我一直在尝试制作一个应用程序，当按下标记结果按钮时，会在用户的当前位置弹出一个地图图钉。

问题是，每当我在 IBAction 中调用 DidUpdateLocations 时，地图注释永远不会出现。但是，如果它在 IBAction 之外，则此功能可以完美运行。当我在 IBAction 内外调用该函数时，会显示连续的地图引脚流。

这是我的代码：

import UIKit
import MapKit
import CoreLocation


class SecondViewController: UIViewController, CLLocationManagerDelegate,MKMapViewDelegate {
@IBOutlet var mapView: MKMapView!
let manager = CLLocationManager()
override func viewDidLoad() {
    super.viewDidLoad()
    manager.delegate = self
    manager.desiredAccuracy = kCLLocationAccuracyBest
    manager.requestWhenInUseAuthorization()
    manager.startUpdatingLocation()

}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

@IBAction func markStuff(_ sender: Any) {
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        let location = locations[0]
        let span:MKCoordinateSpan = MKCoordinateSpanMake(0.001, 0.001)
        let myLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
        let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span)
        let annotation = MKPointAnnotation()
        annotation.coordinate = location.coordinate
        mapView.setRegion(region, animated: true)
        self.mapView.addAnnotation(annotationz)
    }

}


}

这是我的 main.storyboard：

Main.Storyboard

Answer 1

首先，将委托函数locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])移到@IBAction func markStuff(_ sender: Any)之外

在self.mapView.addAnnotation(annotationz)行之后，添加这行：manager.stopUpdatingLocation()，否则它会继续更新你的位置，从而调用委托方法，并添加另一个pin。

不要在viewDidLoad 中调用manager.startUpdatingLocation()，而是在按下按钮时调用它。更新后的代码应如下所示：

import UIKit
import MapKit
import CoreLocation


class SecondViewController: UIViewController, CLLocationManagerDelegate,MKMapViewDelegate {
    @IBOutlet var mapView: MKMapView!
    let manager = CLLocationManager()

    override func viewDidLoad() {
        super.viewDidLoad()
        manager.delegate = self
        manager.desiredAccuracy = kCLLocationAccuracyBest
        manager.requestWhenInUseAuthorization()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    @IBAction func markStuff(_ sender: Any) {

        manager.startUpdatingLocation()

    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        let location = locations[0]
        let span:MKCoordinateSpan = MKCoordinateSpanMake(0.001, 0.001)
        let myLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
        let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span)
        let annotation = MKPointAnnotation()
        annotation.coordinate = location.coordinate
        mapView.setRegion(region, animated: true)
        self.mapView.addAnnotation(annotationz)
        manager.stopUpdatingLocation()
    }

}

locationManager(manager:didUpdate...) 没有被调用，因为它在按钮的操作方法中......它被调用是因为 locationManager 已经更新了位置。它会继续更新你的位置，直到你告诉它，通过调用manager.stopUpdatingLocation()。