Question

我正在使用Swift学习iOS 8应用程序开发。我已经按照Treehouse上的教程指导您在Swift和iOS 8中构建天气应用程序。

作为对应用的改进，作者/导师建议使用CLLocationManager来获取设备的位置以提供给天气API而不是硬编码的纬度和经度值。

因此，在网上阅读了各种教程后，我继续尝试实施这一建议的改进。

我已经将代码放在AppDelegate.swift文件中获取位置坐标。

AppDelegate.swift代码

import UIKit
import CoreLocation

@UIApplicationMain

class AppDelegate: UIResponder, UIApplicationDelegate, CLLocationManagerDelegate {

    var window: UIWindow?
    var locationManager: CLLocationManager!
    var errorOccured: Bool = false
    var foundLocation: Bool = false
    var locationStatus: NSString = "Not Started"
    var location: CLLocationCoordinate2D?
    var locationName: String?


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        // Override point for customization after application launch.
        application.setStatusBarHidden(true, withAnimation: .None)
        initializeLocationManager()
        return true
    }

    func initializeLocationManager() {
        self.locationManager = CLLocationManager()
        self.locationManager.delegate = self
        self.locationManager.desiredAccuracy = kCLLocationAccuracyKilometer
        self.locationManager.requestAlwaysAuthorization()
        self.locationManager.startUpdatingLocation()
    }

    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
        println("didUpdateLocations running")
        if (foundLocation == false) {
            self.locationManager.stopUpdatingLocation()
            foundLocation = true
            var locationArray = locations as NSArray
            var locationObj = locationArray.lastObject as CLLocation
            var geoCoder = CLGeocoder()
            geoCoder.reverseGeocodeLocation(locationObj, completionHandler: { (placemarks, error) -> Void in
                var p = placemarks as NSArray
                var placemark: CLPlacemark? = p.lastObject as? CLPlacemark
                self.locationName = placemark?.name
            })
            self.location = locationObj.coordinate
        }
    }

    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {
        locationManager.stopUpdatingLocation()
        if ((error) != nil) {
            if (errorOccured == false) {
                errorOccured = true
                print(error)
            }
        }
    }

    // authorization status
    func locationManager(manager: CLLocationManager!,
        didChangeAuthorizationStatus status: CLAuthorizationStatus) {
            var shouldIAllow = false

            switch status {
            case CLAuthorizationStatus.Restricted:
                locationStatus = "Restricted Access to location"
            case CLAuthorizationStatus.Denied:
                locationStatus = "User denied access to location"
            case CLAuthorizationStatus.NotDetermined:
                locationStatus = "Status not determined"
            default:
                locationStatus = "Allowed to location Access"
                shouldIAllow = true
            }
            NSNotificationCenter.defaultCenter().postNotificationName("LabelHasbeenUpdated", object: nil)
            if (shouldIAllow == true) {
                NSLog("Location to Allowed")
                // Start location services
                locationManager.startUpdatingLocation()
            } else {
                NSLog("Denied access: \(locationStatus)")
            }
    }

}

然后在我的ViewController.swift文件中，我想获取位置坐标。这是代码：

ViewController.swift代码

func getCurrentWeatherData() -> Void {
    let baseURL = NSURL(string: "https://api.forecast.io/forecast/\(apiKey)/")
    var forecastURL: NSURL
    var locName = "London"

    let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
    appDelegate.foundLocation = false

    if let loc = appDelegate.location {
        println("Got Location!") // for debug purposes
        var currentLat = loc.latitude
        var currentLng = loc.longitude
        forecastURL = NSURL(string: "\(currentLat),\(currentLng)", relativeToURL: baseURL)
        locName = appDelegate.locationName!
    } else {
        println("No Location :(") // for debug purposes
        var currentLat = "51.513445"
        var currentLng = "-0.157828"
        forecastURL = NSURL(string: "\(currentLat),\(currentLng)", relativeToURL: baseURL)
    }

    let sharedSession = NSURLSession.sharedSession()

    let downloadTask: NSURLSessionDownloadTask = sharedSession.downloadTaskWithURL(forecastURL, completionHandler: { (location: NSURL!, response: NSURLResponse!, error: NSError!) -> Void in
        var urlContents = NSString.stringWithContentsOfURL(location, encoding: NSUTF8StringEncoding, error: nil)
        if (error == nil) {
            let dataObject = NSData(contentsOfURL: location)
            let weatherDictionary: NSDictionary = NSJSONSerialization.JSONObjectWithData(dataObject, options: nil, error: nil) as NSDictionary
            let currentWeather = Current(weatherDictionary: weatherDictionary)
            dispatch_async(dispatch_get_main_queue(), {
                () -> Void in
                self.locationNameLabel.text = "\(locName)"
                self.temperatureLabel.text = "\(currentWeather.temperature)"
                self.iconView.image = currentWeather.icon!
                self.currentTimeLabel.text = "At \(currentWeather.currentTime!) it is"
                self.humidityLabel.text = "\(currentWeather.humidity)"
                self.percipitationLabel.text = "\(currentWeather.percipProbability)"
                self.summaryLabel.text = "\(currentWeather.summary)"
                // Stop refresh animation
                self.refreshActivityIndicator.stopAnimating()
                self.refreshActivityIndicator.hidden = true
                self.refreshButton.hidden = false
            })
        } else {
            let networkIssueController = UIAlertController(title: "Error", message: "Unable to load data. Connectivity error!", preferredStyle: .Alert)
            let okButton = UIAlertAction(title: "OK", style: .Default, handler: nil)
            networkIssueController.addAction(okButton)
            let cancelButton = UIAlertAction(title: "Cancel", style: .Cancel, handler: nil)
            networkIssueController.addAction(cancelButton)
            self.presentViewController(networkIssueController, animated: true, completion: nil)

            dispatch_async(dispatch_get_main_queue(), { () -> Void in
                self.refreshActivityIndicator.stopAnimating()
                self.refreshActivityIndicator.hidden = true
                self.refreshButton.hidden = false
            })
        }
    })

    downloadTask.resume()
}

以上无效。我的didUpdateLocations代表从未被调用过。在调试控制台/输出中，我总是打印出No Location :(，表示获取位置失败，更具体地说明我的AppDelegate上的位置属性为nil。

我采取了一些措施来解决这个问题：

在info.plist中，我添加了两个键NSLocationWhenInUseUsageDescription和NSLocationAlwaysUsageDescription
确保我通过WiFi而非以太网连接

无数其他代码调整，但仍然没有。

Answer 1

有几点意见：

正如您所指出的，如果您要致电requestAlwaysAuthorization，则必须设置NSLocationAlwaysUsageDescription。如果您致电requestWhenInUseAuthorization，则需要NSLocationWhenInUseUsageDescription。（您看到确认对话框意味着您已正确完成此操作。我假设您在确认提醒中看到了您提供的任何描述。）
在您的模拟器上，您可能无法在设备上看到位置更新。在实际设备上测试。

当我使用您的代码时，当我从设备调用此代码时，我会看到didUpdateLocations，但不是来自模拟器。
一旦解决了未看到didUpdateLocations的问题，就会出现另一个问题：

您在授权状态更改时发布通知，但不是在异步接收位置时（即稍后）。坦率地说，从视图控制器的角度来看，后者是更重要的事件，所以我认为（a）你应该在收到位置时发布通知; （b）视图控制者应遵守此通知。现在，即使您成功调用didUpdateLocations，视图控制器也不会收到通知。

此外，您的didUpdateLocations正在启动另一个异步过程，即坐标的地理编码。如果您的视图控制器也需要它，您应该在地理编码器的完成块内发布通知。

坦率地说，您甚至没有向我们展示视图控制器代码，该代码为此CLLocationManagerDelegate代码将调用的任何通知添加观察者，但我认为您已经这样做了。

Answer 2

仅供记录：我首先将两个键（NSLocationAlwaysUsageDescription和NSLocationWhenInUseUsageDescription）放入test-plist而不是application-plist。我花了一些时间才意识到.....

CLLocationManager didUpdateLocations未被调用

2 个答案: