从后台任务启动iOS 7中的位置管理器

Question

在iOS 7中，应用程序似乎无法再从后台任务启动位置管理器（通过调用startUpdatingLocation）。

在iOS 6中，我使用了下面描述的方法：https://stackoverflow.com/a/6465280每n分钟运行一次后台位置更新。其想法是使用计时器运行后台任务，并在计时器触发时启动位置管理器。之后，关闭位置管理器并启动另一个后台任务。

更新到iOS 7后，这种方法不再有效。启动Location Manager后，应用程序不会收到任何locationManager:didUpdateLocations。有什么想法吗？

Answer 1

实现此功能的步骤如下：

>

添加位置更新的应用程序寄存器在项目info.plist中的所需背景模式的第0项中。

在应用程序未完成启动时编写以下代码。

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(startFetchingLocationsContinously) name:START_FETCH_LOCATION object:nil];

从您希望开始跟踪的位置编写以下代码

[[NSNotificationCenter defaultCenter] postNotificationName:START_FETCH_LOCATION object:nil];

AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
            [appDelegate startUpdatingDataBase];

将以下代码粘贴到App委托. m

#pragma mark - Location Update
-(void)startFetchingLocationsContinously{
    NSLog(@"start Fetching Locations");
    self.locationUtil = [[LocationUtil alloc] init];
    [self.locationUtil setDelegate:self];
    [self.locationUtil startLocationManager];
}

-(void)locationRecievedSuccesfullyWithNewLocation:(CLLocation*)newLocation oldLocation:(CLLocation*)oldLocation{
    NSLog(@"location received successfullly in app delegate for Laitude: %f and Longitude:%f, and Altitude:%f, and Vertical Accuracy: %f",newLocation.coordinate.latitude,newLocation.coordinate.longitude,newLocation.altitude,newLocation.verticalAccuracy);
}

-(void)startUpdatingDataBase{
    UIApplication*    app = [UIApplication sharedApplication];

    bgTask = UIBackgroundTaskInvalid;

    bgTask = [app beginBackgroundTaskWithExpirationHandler:^(void){
        [app endBackgroundTask:bgTask];
    }];

    SAVE_LOCATION_TIMER =  [NSTimer scheduledTimerWithTimeInterval:300
                                                            target:self selector:@selector(startFetchingLocationsContinously) userInfo:nil repeats:YES];
}

添加名为“LocationUtil”的类，并将以下代码粘贴到头文件中：

#import <Foundation/Foundation.h>
#import <CoreLocation/CoreLocation.h>
@protocol LocationRecievedSuccessfully <NSObject>
@optional
-(void)locationRecievedSuccesfullyWithNewLocation:(CLLocation*)newLocation oldLocation:(CLLocation*)oldLocation;
-(void)addressParsedSuccessfully:(id)address;

@end
@interface LocationUtil : NSObject <CLLocationManagerDelegate> {
}

//Properties
@property (nonatomic,strong) id<LocationRecievedSuccessfully> delegate;
-(void)startLocationManager;

并将以下代码粘贴到LocationUtil中。M

-(void)startLocationManager{

     locationManager = [[CLLocationManager alloc] init];
     locationManager.delegate = self;
     [locationManager setPausesLocationUpdatesAutomatically:YES]; //Utkarsh 20sep2013
     //[locationManager setActivityType:CLActivityTypeFitness];
     locationManager.distanceFilter = kCLDistanceFilterNone;
     locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
     [locationManager startUpdatingLocation];

     //Reverse Geocoding.
     geoCoder=[[CLGeocoder alloc] init];

    //set default values for reverse geo coding.
}

//for iOS<6
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
  //call delegate Method
  [delegate locationRecievedSuccesfullyWithNewLocation:newLocation oldLocation:oldLocation];

  NSLog(@"did Update Location");
}

//for iOS>=6.

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

  CLLocation *newLocation = [locations objectAtIndex:0];
  CLLocation *oldLocation = [locations objectAtIndex:0];

  [delegate locationRecievedSuccesfullyWithNewLocation:newLocation oldLocation:oldLocation];
  NSLog(@"did Update Locationsssssss");
}

Answer 2

我试过你的方法，但对我来说不起作用。你能给我看看你的密码吗？

我实际上在iOS7中找到了解决位置服务问题的解决方案。

在iOS 7中，您无法在后台启动位置服务。如果你想让定位服务在后台继续运行，你必须在前台启动它，它将继续在后台运行。

如果你像我一样，停止定位服务，并在后台使用计时器重新启动它，它将无法在iOS7工作。

有关更多详细信息，您可以观看WWDC 2013的视频307的前8分钟：https://developer.apple.com/wwdc/videos/

更新：定位服务也可以在后台工作。请查看未在iOS 7中运行的后台位置服务，以获取在Github上发布的完整解决方案的更新帖子以及解释详细信息的博客帖子。

Answer 3

我找到了问题/解决办法。当该启动定位服务并停止后台任务时，后台任务应该延迟停止（我用了1秒）。否则定位服务将无法启动。此外，位置服务应该保持打开几秒钟（在我的例子中是3秒）。

另一个重要的注意事项是，iOS 7的最大后台时间现在是3分钟，而不是10分钟。

更新日期：2016年10月29日

有一个cocoapod APScheduledLocationManager，它允许每隔n秒以所需的位置精度获取背景位置更新。

let manager = APScheduledLocationManager(delegate: self)
manager.startUpdatingLocation(interval: 170, acceptableLocationAccuracy: 100)

存储库还包含一个用Swift 3编写的示例应用程序。

更新日期：2014年5月27日

目标C示例：

1）在. plist文件中，将UIBackground Modes设置为位置。

2） 在需要的任何位置创建ScheduledLocationManager的实例。

@property (strong, nonatomic) ScheduledLocationManager *slm;

3） 设置它

self.slm = [[ScheduledLocationManager alloc]init];
self.slm.delegate = self;
[self.slm getUserLocationWithInterval:60]; // replace this value with what you want, but it can not be higher than kMaxBGTime

4） 实现委托方法

-(void)scheduledLocationManageDidFailWithError:(NSError *)error
{
    NSLog(@"Error %@",error);
}

-(void)scheduledLocationManageDidUpdateLocations:(NSArray *)locations
{
    // You will receive location updates every 60 seconds (value what you set with getUserLocationWithInterval)
    // and you will continue to receive location updates for 3 seconds (value of kTimeToGetLocations).
    // You can gather and pick most accurate location
    NSLog(@"Locations %@",locations);
}

以下是ScheduledLocationManager的实现：

#########################################################################################

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

@protocol ScheduledLocationManagerDelegate <NSObject>

-(void)scheduledLocationManageDidFailWithError:(NSError*)error;
-(void)scheduledLocationManageDidUpdateLocations:(NSArray*)locations;

@end

@interface ScheduledLocationManager : NSObject <CLLocationManagerDelegate>

-(void)getUserLocationWithInterval:(int)interval;

@end

下载位置管理器

#import "ScheduledLocationManager.h"

int const kMaxBGTime = 170; // 3 min - 10 seconds (as bg task is killed faster)
int const kTimeToGetLocations = 3; // time to wait for locations

@implementation ScheduledLocationManager
{
    UIBackgroundTaskIdentifier bgTask;
    CLLocationManager *locationManager;
    NSTimer *checkLocationTimer;
    int checkLocationInterval;
    NSTimer *waitForLocationUpdatesTimer;
}

- (id)init
{
    self = [super init];
    if (self) {
        locationManager = [[CLLocationManager alloc] init];
        locationManager.delegate = self;
        locationManager.desiredAccuracy = kCLLocationAccuracyBest;
        locationManager.distanceFilter = kCLDistanceFilterNone;

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationDidEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationDidBecomeActive:) name:UIApplicationDidBecomeActiveNotification object:nil];
    }
    return self;
}

-(void)getUserLocationWithInterval:(int)interval
{
    checkLocationInterval = (interval > kMaxBGTime)? kMaxBGTime : interval;
    [locationManager startUpdatingLocation];
}

- (void)timerEvent:(NSTimer*)theTimer
{
    [self stopCheckLocationTimer];
    [locationManager startUpdatingLocation];

    // in iOS 7 we need to stop background task with delay, otherwise location service won't start
    [self performSelector:@selector(stopBackgroundTask) withObject:nil afterDelay:1];
}

-(void)startCheckLocationTimer
{
    [self stopCheckLocationTimer];
    checkLocationTimer = [NSTimer scheduledTimerWithTimeInterval:checkLocationInterval target:self selector:@selector(timerEvent:) userInfo:NULL repeats:NO];
}

-(void)stopCheckLocationTimer
{
    if(checkLocationTimer){
        [checkLocationTimer invalidate];
        checkLocationTimer=nil;
    }
}

-(void)startBackgroundTask
{
    [self stopBackgroundTask];
    bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        //in case bg task is killed faster than expected, try to start Location Service
        [self timerEvent:checkLocationTimer];
    }];
}

-(void)stopBackgroundTask
{
    if(bgTask!=UIBackgroundTaskInvalid){
        [[UIApplication sharedApplication] endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }
}

-(void)stopWaitForLocationUpdatesTimer
{
    if(waitForLocationUpdatesTimer){
        [waitForLocationUpdatesTimer invalidate];
        waitForLocationUpdatesTimer =nil;
    }
}

-(void)startWaitForLocationUpdatesTimer
{
    [self stopWaitForLocationUpdatesTimer];
    waitForLocationUpdatesTimer = [NSTimer scheduledTimerWithTimeInterval:kTimeToGetLocations target:self selector:@selector(waitForLoactions:) userInfo:NULL repeats:NO];
}

- (void)waitForLoactions:(NSTimer*)theTimer
{
    [self stopWaitForLocationUpdatesTimer];

    if(([[UIApplication sharedApplication ]applicationState]==UIApplicationStateBackground ||
        [[UIApplication sharedApplication ]applicationState]==UIApplicationStateInactive) &&
       bgTask==UIBackgroundTaskInvalid){
        [self startBackgroundTask];
    }

    [self startCheckLocationTimer];
    [locationManager stopUpdatingLocation];
}

#pragma mark - CLLocationManagerDelegate methods

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    if(checkLocationTimer){
        //sometimes it happens that location manager does not stop even after stopUpdationLocations
        return;
    }

    if (self.delegate && [self.delegate respondsToSelector:@selector(scheduledLocationManageDidUpdateLocations:)]) {
        [self.delegate scheduledLocationManageDidUpdateLocations:locations];
    }

    if(waitForLocationUpdatesTimer==nil){
        [self startWaitForLocationUpdatesTimer];
    }
}

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
    if (self.delegate && [self.delegate respondsToSelector:@selector(scheduledLocationManageDidFailWithError:)]) {
        [self.delegate scheduledLocationManageDidFailWithError:error];
    }
}

#pragma mark - UIAplicatin notifications

- (void)applicationDidEnterBackground:(NSNotification *) notification
{
    if([self isLocationServiceAvailable]==YES){
        [self startBackgroundTask];
    }
}

- (void)applicationDidBecomeActive:(NSNotification *) notification
{
    [self stopBackgroundTask];
    if([self isLocationServiceAvailable]==NO){
        NSError *error = [NSError errorWithDomain:@"your.domain" code:1 userInfo:[NSDictionary dictionaryWithObject:@"Authorization status denied" forKey:NSLocalizedDescriptionKey]];

        if (self.delegate && [self.delegate respondsToSelector:@selector(scheduledLocationManageDidFailWithError:)]) {
            [self.delegate scheduledLocationManageDidFailWithError:error];
        }
    }
}

#pragma mark - Helpers

-(BOOL)isLocationServiceAvailable
{
    if([CLLocationManager locationServicesEnabled]==NO ||
       [CLLocationManager authorizationStatus]==kCLAuthorizationStatusDenied ||
       [CLLocationManager authorizationStatus]==kCLAuthorizationStatusRestricted){
        return NO;
    }else{
        return YES;
    }
}

@end