swift - 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)"

提前感谢您的帮助。

Answer 1

如果设备没有移动，或者移动速度足够慢以至于数学没有意义，Core Location 会给你一个负速度值。

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