xcode - 为什么我会收到 fatal error : unexpectedly found nil while unwrapping an optional value. .. 这是我的代码:

Question

不确定为什么这不起作用？任何帮助将不胜感激。谢谢。

import UIKit
import MapKit
import CoreLocation

class ViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {

    var locationManager:CLLocationManager!
    @IBOutlet weak var mapView: MKMapView!

    @IBAction func nowButton(sender: AnyObject) {
    }

    @IBOutlet weak var mapLabel: UILabel!

    @IBAction func bookButton(sender: AnyObject) {       
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager = CLLocationManager()
        locationManager.requestAlwaysAuthorization()        
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.delegate = self
        locationManager.startUpdatingLocation()

        mapView.showsUserLocation = true
        mapView.delegate = self

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

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

    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
        let regionToZoom = MKCoordinateRegionMake(manager.location.coordinate, MKCoordinateSpanMake(0.05, 0.05))
        mapView.setRegion(regionToZoom, animated: true)
    }

}

Answer 1

可能的错误原因在于 didUpdateLocations 委托(delegate)方法中的这一行:

let regionToZoom = MKCoordinateRegionMake(manager.location.coordinate, MKCoordinateSpanMake(0.05, 0.05))

您需要像下面的行一样创建区域(用上面的行替换此行):

let regionToZoom = MKCoordinateRegion(center: manager.location.coordinate, span: MKCoordinateSpanMake(0.05, 0.05)));