Question

有人可以帮我理解为什么在下面的代码中会有这样的输出：

[1 + 37.49638550，-122.31160280＆GT; +/- 5.00米（速度32.65 mps /航向   294.26）@ 7/27 / 16,4：34：19 AM东部夏令时间]

n / a Belmont Belmont

Belmont 1

也就是说，为什么变量locality在特定点打印时具有值“n / a”，而localityVC＆amp; localityGlobal从不这样做？这纯粹是范围问题还是与CLGeocoder()有关？感谢

import UIKit
import MapKit
import CoreLocation

var localityGlobal: String = "n/a"

class ViewController: UIViewController, CLLocationManagerDelegate {

    let locationManager = CLLocationManager()
    var localityVC: String = "n/a"

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        print("hello")

        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.requestWhenInUseAuthorization()
        locationManager.startUpdatingLocation()
    }

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

        let userLocation: CLLocation = locations[0]
        var locality: String = "n/a"

        CLGeocoder().reverseGeocodeLocation(userLocation, completionHandler: {(placemarks, error) -> Void in
            if error != nil {
                print("CLGeocoder.reverseGeocodeLocation() failed")
                return
            }
            if placemarks!.count > 0 {
                locality = placemarks![0].locality!
                self.localityVC = placemarks![0].locality!
                localityGlobal = placemarks![0].locality!
                print(locality, placemarks!.count)

            } else {
                print("CLGeocoder.reverseGeocodeLocation() error in geocoder data")
            }
        })

        print(locality, localityVC, localityGlobal)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

为了使上述内容能够运行，您还需要：

Build Phases -> Link Binary with Libraries包含 CoreLocation.framework，
Info.plist必须包含变量 NSLocationWhenInUseUsageDescription和 NSLocationAlwaysUsageDescription设置，
Simulator -> Debug -> Location设置为Apple，City Bicycle Ride，City Run或Freeway Drive

我正在运行xcode 7.3.1（7D1014）

Answer 1

这不是范围问题，而是时间问题。你得到n / a，因为在执行print语句时闭包还没有运行。

其他变量保留先前调用的值。

关闭wrt的快速变量范围CLGeocoder（）

1 个答案: