Question

我在视图出现时开始更新当前位置，并在调用locationManager:didUpdateLocations:时停止更新位置。但为什么总是多次调用locationManager:didUpdateLocations:？我错过了什么？

#import "ViewController.h"

@interface ViewController (){
    CLLocationManager *locationManager; // location manager for current location
}
@end

@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self startUpdatingCurrentLocation];
}

- (void)startUpdatingCurrentLocation
{
    if (!locationManager)
    {
        locationManager = [[CLLocationManager alloc] init];
        [locationManager setDelegate:self];
        locationManager.distanceFilter = 10.0f; // we don't need to be any more accurate than 10m
    }
    [locationManager startUpdatingLocation];
}

-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{
    [locationManager stopUpdatingLocation];
}
@end

Answer 1

可能这取决于您为locationManager设置的准确度。你有3种本地化的Cell Radio，WiFi Map，GPS。如果您将精度设置为最佳，位置管理器将继续检查您的位置，如果精度更高的位置超出距离过滤器的范围，则将再次调用委托方法。

Answer 2

SWIFT版

我创建了一个帮助类HelperLocationManager并添加了notification- observer模式

import UIKit
import CoreLocation



class HelperLocationManager: NSObject {

    var locationManager = CLLocationManager()
    static let sharedInstance = HelperLocationManager()
    var currentLocation :CLLocation?
    var notGotUserLocation = true

    override init() {

        super.init()

        var code = CLLocationManager.authorizationStatus()

        if code == CLAuthorizationStatus.NotDetermined {

            locationManager.requestAlwaysAuthorization()
            locationManager.requestWhenInUseAuthorization()

        }
        locationManager.requestAlwaysAuthorization()
        locationManager.requestWhenInUseAuthorization()
        locationManager.delegate = self
        locationManager.distanceFilter = 100;

    }


}


extension HelperLocationManager: CLLocationManagerDelegate{


    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {

            var locValue = locations.last as! CLLocation
            println(locValue)
            self.currentLocation = locValue
            NSNotificationCenter.defaultCenter().postNotificationName("sendCurrentAddressToViewController", object:self.currentLocation)
            notGotUserLocation = false


    }

    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {

        println("Your error is ", error.localizedDescription)

    }


}

现在，如果您的Viewcontroller课程需要该位置，那么请将观察者放在那里

var helperLocation:HelperLocationManager?

在viewDidLoad中

     override func viewDidLoad() {

         helperLocation = HelperLocationManager()
         NSNotificationCenter.defaultCenter().addObserver(self, selector: "getCurrentAddressToViewController:", name: "sendCurrentAddressToViewController", object: nil)

  }

//和观察者

 func getCurrentAddressToViewController(notification: NSNotification) {

        currentLocation = notification.object as? CLLocation
        NSNotificationCenter.defaultCenter().removeObserver(self, name: "sendCurrentAddressToViewController", object: nil)

    }

//虽然多次调用didUpdateLocation，但由于在获取位置后删除了observer，因此只能获得一次位置。

编辑：我重写了这个助手类，这样你就不需要添加notificationobserver模式

class HelperLocationManager: NSObject {

    private lazy var locationManager = CLLocationManager()
    static let sharedInstance = HelperLocationManager()
    var currentLocation :CLLocation?

    override init() {

        super.init()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.delegate = self
    }
}

extension HelperLocationManager: CLLocationManagerDelegate{

    func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {

        switch status {

        case CLAuthorizationStatus.NotDetermined:

            locationManager.requestWhenInUseAuthorization()


        case CLAuthorizationStatus.Restricted:

            PrinterHelper.messagePrinter("Restricted Access to location")

        case CLAuthorizationStatus.Denied:

            PrinterHelper.messagePrinter("User denied access to location")

        case CLAuthorizationStatus.AuthorizedWhenInUse:

            if #available(iOS 9.0, *) {

                locationManager.requestLocation()

            } else {

                locationManager.startUpdatingLocation()
            }

        default:

            PrinterHelper.messagePrinter("default authorization")

        }
    }

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

        let locValue = locations.last
        HelperLocationManager.sharedInstance.currentLocation =  locValue
        locationManager.stopUpdatingLocation()

    }

    func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {

        PrinterHelper.errorPrinter(error.localizedDescription)

    }
}

查看需要获取用户权限的控制器

var helperLocationManager:HelperLocationManager?

在viewDidLoad中

     override func viewDidLoad() {

         helperLocationManager = HelperLocationManager.sharedInstance


  }

要获取您需要将单身人士属性currentLocation称为

的位置

 if  let userCurentLoc = HelperLocationManager.sharedInstance.currentLocation{

           //userCurrentLoc is the user Location

        }

Answer 3

为了补充Anish的答案，如果你想知道你的帮助班什么时候没有调用位置更新（即你关闭了你的位置服务），你可以使用{{{ 1}}方法，如果您的位置不被允许，您可以拨打另一个locationManager:didChangeAuthorizationStatus:

notification- observer

locationManager：didUpdateLocations：总是被多次调用

3 个答案: