swift - 按下按钮时的当前位置 map 图钉

Question

我一直在尝试制作一个应用程序，当按下标记调查结果按钮时， map 图钉会在用户的当前位置弹出。

问题是，每当我在 IBAction 中调用 DidUpdateLocations 时， map 注释永远不会出现。但是，如果这个函数在 IBAction 之外，它就可以完美地工作。当我在 IBAction 外部和内部调用该函数时，会显示连续的 map 图钉流。

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)
    }

}


}

这是我的主要 Storyboard:

Main.Storyboard

Answer 1

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

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，因此调用委托(delegate)方法，并添加另一个引脚。

不是在 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...) 未被调用，因为它在您按钮的操作方法中...它被调用是因为 locationManager 已更新位置。它将继续更新您的位置，直到您通过调用 manager.stopUpdatingLocation() 另行通知它为止。