CoreLocation用户速度

Question

我目前正在尝试获取当前用户的设备移动速度。这里是我的代码：

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)") 
} 

唯一的问题是，它打印"Optional(-1,0)"

感谢提前的帮助。

Answer 1

如果设备没有移动，或者移动速度缓慢，数学没有意义，核心位置会给速度带来负值。

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

Answer 2

只需更换？与！像

print(manager.location!.speed) 

日志的变化之后是

0.0