ios - didUpdateLocations 每次当 viewWillAppear 发生重大位置变化时调用

Question

我在同一个 UIViewController 中使用 CLLocationManager 和 MKMapView。我只想在重要位置发生变化时调用 API。

import UIKit
import CoreLocation
import MapKit


class ViewController: UIViewController,CLLocationManagerDelegate,MKMapViewDelegate {

@IBOutlet weak var mapView: MKMapView!

var locationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    self.locationManager.requestAlwaysAuthorization()
    self.locationManager.delegate = self
    self.locationManager.startMonitoringSignificantLocationChanges()
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation
    self.locationManager.distanceFilter = 500
    mapView.showsUserLocation = true
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)
}


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

public func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        print("locations \(locations)")
 }

}

在此，主要问题是每当我调用应用程序背景和前景 didUpdateLocations 时。我希望仅在位置发生重大变化时调用它，而不是每次调用 viewWillAppear 时调用它。

我发现它是因为 MKMapView，正在调用 didUpdateLocations。

Answer 1

您可以手动检查与上次保存位置的距离。试试这个。

var lastLocation: CLLocation?
public func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

    if let lastLocation = lastLocation, let newLocation = locations.last {
        if (lastLocation.distance(from: newLocation) < manager.distanceFilter) {
            return
        }
    }

    print("locations \(locations)")
    lastLocation =  locations.last
}