使用Swift CoreLocation获取经度和纬度

Question

I am trying to use CoreLocation to get the latitude and longitude coordinates in iOS 8. After looking through a lot of posts, I am still unsure how to go about doing this. Also, I would appreciate a brief explanation of the locationManager() methods as I don't understand what role they play in obtaining the location. Do I ever need to call these methods? Because I never saw them called in any examples.

class ViewController: UIViewController, CLLocationManagerDelegate {

var locationMan = CLLocationManager()
var ourLocation: CLLocation!

override func viewDidLoad() {

    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    self.locationMan.delegate = self
    self.locationMan.desiredAccuracy = kCLLocationAccuracyBest
    self.locationMan.requestWhenInUseAuthorization()
    self.locationMan.startUpdatingLocation()
}

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

func locationManager(manager: CLLocationManager!, didUpdateLocations locations : [AnyObject]!){
    locationMan.stopUpdatingLocation()
    ourLocation = locations[0] as! CLLocation
}

func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {
    println("Error: " + error.localizedDescription)
}

@IBAction func button(sender: AnyObject) {
    var testClass:item = item()

After the next line, the app crashes and I get the error: fatal error: unexpectedly found nil while unwrapping an Optional value. I think this means that ourLocation never actually gets set. (Note that I am casting to float because I need to store the location as a float on my server)

    testClass.lat = Float(ourLocation.coordinate.latitude)
    println(testClass.lat)
    testClass.long = Float(ourLocation.coordinate.longitude)
    println(testClass.long)
    testClass.name = "Nice"
    testClass.description = "Wow this is pretty cool"
    testClass.postItemToServer()
    }
}

Note that I have updated my plist file appropriately! Location is turned on in the simulator.

Answer 1

Check if the values you are passing to variable are nil or not

if  ourLocation.coordinate.latitude != nil
{
  testClass.lat = Float(ourLocation.coordinate.latitude)
  println(testClass.lat)
}

Also check for longitude.

Answer 2

import UIKit
import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate{

    var manager:CLLocationManager!
    var location : CLLocation!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.
        self.manager = CLLocationManager()
        self.manager.delegate = self;
        self.manager.desiredAccuracy = kCLLocationAccuracyBest
        self.manager.requestWhenInUseAuthorization()
        self.manager.startUpdatingLocation()


    }

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

    func locationManager(manager: CLLocationManager!, didUpdateLocations locations : [AnyObject]!){
        manager?.stopUpdatingLocation()
        self.location = locations[0] as CLLocation
    }

    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {
        println("Error: " + error.localizedDescription)
    }

    @IBAction func button(sender: AnyObject) {

        //check if location is not nil
        if self.location != nil {

            //assign your loaction values here
            let lat = Float(location.coordinate.latitude)
            let long = Float(location.coordinate.longitude)

        } else {
            println("locationManager.location is nil")
        }

    }


}

The location property is an implicitly unwrapped CLLocation optional, and it is likely nil. You should never access members of implicitly unwrapped optional unless you know it is not nil.