CoreLocation用戶速度

Question

我目前正在嘗試獲取當前用戶的設備移動速度。這裏是我的代碼：

import UIKit 
import Foundation 
import CoreLocation 

class ViewController: UIViewController, CLLocationManagerDelegate { 

let manager = CLLocationManager() 
var currentSpeed = 0.0 

override func viewDidLoad() { 
    super.viewDidLoad() 

    manager.requestWhenInUseAuthorization() 

    manager.delegate = self 
    manager.desiredAccuracy = kCLLocationAccuracyHundredMeters 
    manager.startUpdatingLocation() 
} 

func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { 
    print(manager.location?.speed) 
} 

func locationManager(manager: CLLocationManager, didFailWithError error: NSError) { 
    print("Error: \(error.localizedDescription)") 
} 

唯一的問題是，它打印"Optional(-1,0)"

感謝提前的幫助。

Answer 1

如果設備沒有移動，或者移動速度緩慢，數學沒有意義，核心位置會給速度帶來負值。

https://developer.apple.com/library/ios/documentation/CoreLocation/Reference/CLLocation_Class/#//apple_ref/occ/instp/CLLocation/speed

Answer 2

只需更換？與！像

print(manager.location!.speed) 

日誌的變化之後是

0.0