ios - 什么在我的 Swift 代码中调用 didUpdateLocations？

Question

我正在学习 Swift，下面的代码片段中有一个 locationManager 方法。即使“定位我”按钮的操作代码中没有调用它，为什么我应该写这个？

import UIKit
import MapKit
import CoreLocation

class ViewController: `UIViewController, CLLocationManagerDelegate` {
  @IBOutlet weak var Mapview: MKMapView!
  var manager = CLLocationManager()

  override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    let pinLocation: CLLocationCoordinate2D = CLLocationCoordinate2DMake(51.5078788, -0.08773210000003928)
    let objectAnn = MKPointAnnotation()
    objectAnn.coordinate = pinLocation
    objectAnn.title = "London Bridge"
    objectAnn.subtitle = "London, United kingdom"
    self.Mapview.addAnnotation(objectAnn)
  }

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

  @IBAction func Directions(sender: AnyObject) {
    UIApplication.sharedApplication().openURL(NSURL(string: "http://maps.apple.com/maps?daddr=51.5078788,-0.08773210000003928")!)
  }

  @IBAction func LocateMe(sender: AnyObject) {
    manager.delegate = self
    manager.desiredAccuracy = kCLLocationAccuracyBest
    manager.requestWhenInUseAuthorization()
    manager.startUpdatingLocation()

    Mapview.showsUserLocation = true
  }

  func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    let userlocation:CLLocation = locations[0] as CLLocation

    manager.stopUpdatingLocation()

    let location = CLLocationCoordinate2D(latitude: userlocation.coordinate.latitude, longitude: userlocation.coordinate.longitude)
    let span = MKCoordinateSpanMake(0.5, 0.5)
    let region = MKCoordinateRegion(center: location, span: span)

    Mapview.setRegion(region, animated: true)
  }
}

Answer 1

它被称为委托(delegate)。

您正在实现 CLLocationManagerDelegate。

由于您使用此代码 manager.delegate = self 将您的 manager 委托(delegate)设置为 View Controller ，它将在特定条件下自动调用委托(delegate)事件。

在你的代码中，如果你的位置更新了， View Controller 会自动运行这个函数func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation])