swift - 在 map View 上使用轨迹位置时出现变量错误

Question

我正在尝试在 map View 上显示和跟踪位置。我收到错误:

Use of local Variable 'locationManager' before declaration

该错误出现在 locationManager 的所有行上:

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

我在 ViewDidLoad 之前声明了 var locationManager = CLLocationManager()。

我的变量是否放在错误的位置？

import UIKit
import MapKit
import CoreLocation

class InfoViewController: UIViewController,UIGestureRecognizerDelegate, CLLocationManagerDelegate {


    // Outlets
    @IBOutlet weak var infoImageView: UIImageView!


    @IBOutlet weak var nameLabel: UILabel!


    @IBOutlet weak var categoryLabel: UILabel!


    @IBAction func urlButton(sender: UIButton) {
    }

    @IBOutlet weak var mapView: MKMapView!

    // Variables

    var gesture: UISwipeGestureRecognizer!

    var store: Store!

    var locationManager = CLLocationManager()




    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.

        // Background image
        self.infoImageView.image = UIImage(data: store.photo)

        // Set label text
        self.nameLabel.text = store.name

        // Set category text
        var categoryText = String()
        for category in store.storeCategories {
            if !categoryText.isEmpty {
                categoryText += ", "
            }
            categoryText += category.name
        }

        categoryLabel.text = categoryText




        if (CLLocationManager.locationServicesEnabled())
        {

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

        }

        func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
            let location = locations.last as! CLLocation

            let center = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
            let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01))

            self.mapView.setRegion(region, animated: true)
            }

        // Gesture recoginizer
        gesture = UISwipeGestureRecognizer(target: self, action: "dismissView")
        self.gesture.direction = UISwipeGestureRecognizerDirection.Up

        self.view.addGestureRecognizer(self.gesture)

    }

    func dismissView() {
        self.dismissViewControllerAnimated(true, completion: nil)
    }


}

Answer 1

您必须在 block 之外声明 locationManager，在本例中，您尝试在 if-block 内声明它。这将使它成为一个局部变量。在 if-block. 之外声明变量该作业的工作示例代码:

var locationManager = CLLocationManager()

override func viewDidLoad() {

如您所见，我已将变量声明为与 viewDidLoad() 相同的级别。方法，赋予它更大的范围。

然后，在 if block 中您可以执行以下操作:

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

请注意，我删除了 locationManager = CLLocationManager() 的第一行因为它已经实例化了。

此外，locationManager 的函数不得位于 viewDidLoad 方法内部。

此外，我不明白为什么你的if-block正在包装该方法。