Question

这是我在ViewController.swift中的代码：

import UIKit
import Alamofire
import SwiftyJSON
import MapKit
import CoreLocation
import TwitterKit

class ViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {

    @IBOutlet weak var myMap: MKMapView!
    @IBOutlet weak var counterLabel: UILabel!

    var manager = CLLocationManager()

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.

        //calling CLLocation
        manager.delegate = self
        manager.desiredAccuracy = kCLLocationAccuracyBest
        manager.requestWhenInUseAuthorization()
        manager.startUpdatingLocation()

        //map region
        let locationZoom = self.manager.location
        var latitude: Double = locationZoom.coordinate.latitude
        var longitude: Double = locationZoom.coordinate.longitude
        var centerLatitude: CLLocationDegrees = locationZoom.coordinate.latitude
        var centerLongitude: CLLocationDegrees = locationZoom.coordinate.longitude
        var latDelta: CLLocationDegrees = 0.03
        var longDelta: CLLocationDegrees = 0.03
        var span: MKCoordinateSpan = MKCoordinateSpanMake(latDelta, longDelta)
        var location: CLLocationCoordinate2D = CLLocationCoordinate2DMake(centerLatitude, centerLongitude)
        var region: MKCoordinateRegion = MKCoordinateRegionMake(location, span) // this creates a map region with the center
        myMap.setRegion(region, animated: true)
    }

    @IBAction func zoom(sender: AnyObject) {


        let locationZoom = self.manager.location

        var latitude: Double = locationZoom.coordinate.latitude
        var longitude: Double = locationZoom.coordinate.longitude
        var centerLatitude:CLLocationDegrees = locationZoom.coordinate.latitude
        var centerLongitude: CLLocationDegrees = locationZoom.coordinate.longitude
        var latDelta:CLLocationDegrees = 0.03
        var longDelta:CLLocationDegrees = 0.03
        var span:MKCoordinateSpan = MKCoordinateSpanMake(latDelta, longDelta)
        var location:CLLocationCoordinate2D = CLLocationCoordinate2DMake(centerLatitude, centerLongitude)
        var region:MKCoordinateRegion = MKCoordinateRegionMake(location, span) // this creates a map region with the center
        myMap.setRegion(region, animated: true)
    }
}

现在，错误描述如下：

致命错误：在解包可选值时意外发现nil

线程1指向这个问题：

var latitude: Double = locationZoom.coordinate.latitude

但是，在模拟器上测试时，我也发现了经度变量的问题。不过，我不明白为什么经度和纬度的值都设置为“零”。我已正确设置CLLocationManager，请确保根据需要修改info.plist以包含NSLocationWhenInUseUsageDescription和NSLocationAlwaysUsageDescription等。发生了什么，以及如何更正此问题？

Answer 1

这是因为当你的视图加载时它没有收到任何位置更新。在那里实施DidUpdateLocations并访问位置信息。如果您需要参考，可以查看DidUpdateLocations

func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {

    let locationZoom = locations.last as! CLLocation
    let latitude: Double = locationZoom.coordinate.latitude
    let longitude: Double = locationZoom.coordinate.longitude
    println(latitude)
    println(longitude)
}

CLLocationManager：在展开可选值时意外地发现了Nil

1 个答案: