ios - 在 locationManager() 之外使用变量

Question

我正在尝试使用 MVC 模式清理我的代码。我有一个文件“CoreLocationService.swift”，我想在其中获取位置。我想在“ViewController.swift”中使用该位置将其显示给用户。

CoreLocationService.swift

import Foundation
import CoreLocation

class CoreLocationService: CLLocationManager, CLLocationManagerDelegate {


    let locationManager = CLLocationManager()

    var latitude : Double?


    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        let GPS = locations[locations.count - 1] // Get the array of last location

        latitude = GPS.coordinate.latitude


    }
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        print(error)
    }


    func GPSInitialize() {
        // Start GPS

        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        //locationManager.requestLocation() // One time request
        locationManager.startUpdatingLocation() // Continues location

    }


}

ViewController.swift

import UIKit
import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate {

//    let location = CLLocationManager()

    let locationService = CoreLocationService() // CoreLocationService Class


    override func viewDidLoad() {
        super.viewDidLoad()


        locationService.GPSInitialize() // Start updating Location


        print(locationService.latitude) // Print Latitude

    }

}

我将 latitude 声明为要访问的全局变量来自 ViewController.swift，但该变量为空并且仅打印“nil”。

如果我在 locationManager 中打印“Print(latitude)”，它会打印坐标。

Answer 1

我认为为什么调用 print(loccationService.latitude) 时纬度为零是委托(delegate)方法

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])

尚未更新纬度。

您可以像下面这样在 CoreLocationService 中添加一个回调，

// callback to be called after updating location
var didUpdatedLocation: (() -> ())?

然后在委托(delegate)方法中调用这个闭包，

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        let GPS = locations[locations.count - 1] // Get the array of last location

        latitude = GPS.coordinate.latitude

        didUpdatedLocation?()
}

在您的 ViewController 中，像这样打印纬度，

locationService.didUpdatedLocation = {
    print(locationService.latitude) // Print Latitude
}

希望这对您有所帮助!