iOS8 CLLocationManager 在后台状态返回 Null

Question

在 iOS8 中，当我将我的应用程序置于后台时，CLLocationManager 在位置中返回 Null，我也无法在后台模式下进行位置更新并且也执行 requestAlwaysAuthorization

    CLLocationManager *lm = [[CLLocationManager alloc] init];
    lm.delegate = self;
    lm.desiredAccuracy = kCLLocationAccuracyBest;
    lm.distanceFilter = kCLDistanceFilterNone;
    [lm requestAlwaysAuthorization];
    [lm startUpdatingLocation];

Answer 1

请在下面找到用于在后台模式下获取位置的代码 -

请在 plist 文件中输入 NSLocationAlwaysUsageDescription 的文本。

请从项目设置中选择后台模式的位置更新 -

AppDelegate.h

//
//  AppDelegate.h
//  LocationTest
//
//  Created by Santu C on 28/05/15.
//  Copyright (c) 2015 company. All rights reserved.
//

#import <UIKit/UIKit.h>
#import<CoreLocation/CoreLocation.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;


@property(strong,nonatomic) CLLocationManager *locationManager;


@end

AppDelegate.m

//
//  AppDelegate.m
//  LocationTest
//
//  Created by Santu C on 28/05/15.
//  Copyright (c) 2015 company. All rights reserved.
//

#import "AppDelegate.h"

@implementation AppDelegate
@synthesize locationManager;

#define CONST_TIME_INTERVAL 60.0

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

    [self location];



    // Override point for customization after application launch.
    return YES;
}



-(void)location
{


    NSLog(@"location called");

    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.delegate = self;
    self.locationManager.distanceFilter = kCLDistanceFilterNone;
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
    self.locationManager.pausesLocationUpdatesAutomatically = NO;

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000

    if ([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)])
    {
        [self.locationManager requestAlwaysAuthorization];
    }
#endif

    [self.locationManager startUpdatingLocation];

}


- (void)startUpdatingLocation
{
    NSLog(@"startUpdatingLocation called");

    self.locationManager.delegate = self;
    [self.locationManager startUpdatingLocation];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{


    NSLog(@"locationManager didUpdateLocations");

    CLLocation *newLocation = (CLLocation *)[locations lastObject];


    NSLog(@"dLongitude : %f", newLocation.coordinate.latitude);
    NSLog(@"dLatitude : %f", newLocation.coordinate.longitude);



}




- (void)applicationDidEnterBackground:(UIApplication *)application
{
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.

     [self startUpdatingLocation];
}



@end

希望对你有帮助