創建全局CLLocationManager時出錯

Question

Apple Docs建議不要將CLLocationManager存儲在本地變量中。所以我創建了一個全局常量，在我的ViewController類的範圍之外，就在import聲明之後。試圖訪問類裏面的常量，然而，拋出編譯器錯誤：

NSMutableDictionary類型的類似聲明globalDictionary常數似乎是類的內部訪問。

這是什麼，我在這裏做錯了？ 爲什麼上述不起作用？

---

代碼：

// 
// ViewController.swift 
// CoreLocationExample 
// 
// 

import UIKit 
import CoreLocation 
import Foundation 

let locationManager = CLLocationManager() 
let globalDictionary = NSMutableDictionary() 
class ViewController: UIViewController, CLLocationManagerDelegate { 

// let locationManager = CLLocationManager() 
    override func viewDidLoad() { 
     super.viewDidLoad() 
     locationManager.delegate = self 
     locationManager.requestWhenInUseAuthorization() 

     let dict = [ 
      "name":"John" 
     ] 
     globalDictionary.addEntries(from: dict) 
     print(globalDictionary) 
    } 
} 

---

上的Xcode版本使用斯威夫特3 8.3.1

Answer 1

你可以做到這一點通過以下方式 -

class LocationTracker { 
static var locationManager: CLLocationManager? = LocationTracker.sharedLocationManager() 

class func sharedLocationManager() -> CLLocationManager { 

    let lockQueue = DispatchQueue(label: "self") 
    lockQueue.sync { 
     if _locationManager == nil { 
      _locationManager = CLLocationManager() 
      _locationManager?.desiredAccuracy = kCLLocationAccuracyBestForNavigation 
      _locationManager?.allowsBackgroundLocationUpdates = true 
      _locationManager?.pausesLocationUpdatesAutomatically = false 
     } 
    } 
    return _locationManager! 
} 

}

而且當你需要調用它在你的代碼，你可以做以下 -

var locationManager: CLLocationManager? = LocationTracker.sharedLocationManager() 

然後你可以在這個類以及像startt跟蹤添加其他位置相關的方法，更新位置，stoptracking等

Answer 2

使用單例類此

進口的UIKit 進口CoreLocation

公共類的LocationManager：NSObject的，CLLocationManagerDelegate {

public static let sharedInstance = LocationManager() 
public lazy var locationManager: CLLocationManager = CLLocationManager() 
var globalDictionary = NSMutableDictionary() 

public override init() { 
    super.init() 
    self.locationManager.requestAlwaysAuthorization() 
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest 
    self.locationManager.distanceFilter = kCLDistanceFilterNone; 
    self.locationManager.startUpdatingLocation() 
    self.locationManager.delegate = self 
    let dict = [ 
     "name":"John" 
    ] 
    self.globalDictionary.addEntries(from: dict) 
    print(self.globalDictionary) 
} 

// MARK: - Location Manager Delegate 
public func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) { 

    print(error) 
} 

public func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]){ 
    let newLocation: CLLocation? = locations.last 
    let locationAge: TimeInterval? = -(newLocation?.timestamp.timeIntervalSinceNow)! 
    if Double(locationAge!) > 5.0 { 
     return 
    } 
    if Double((newLocation?.horizontalAccuracy)!) < 0 { 
     return 
    } 
} 

public func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) { 

} 

}

Answer 3

蘋果文檔建議不要你CLLocationManager存儲在一個局部變量。 這意味着不要在方法/函數中創建本地實例。

請聲明這樣。

類的AppDelegate：UIResponder，UIApplicationDelegate {

//CLLocation Manager 
let locationManager = CLLocationManager() 
var locValue = CLLocationCoordinate2D() 

}

CLLocation經理或globalDictionary類裏面。