Question

我有更新用户位置的奇怪问题。有时我的应用程序会更新位置，但有时会更新。我不知道问题出在哪里，我的代码（来自AppDelegate.m）如下：

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    NSLog(@"Went to Background");
    // Only monitor significant changes
    [locationManager startMonitoringSignificantLocationChanges];
}


- (void)applicationDidBecomeActive:(UIApplication *)application
{
    // Start location services
    locationManager = [[CLLocationManager alloc] init];
    locationManager.desiredAccuracy = kCLLocationAccuracyBest;

    // Only report to location manager if the user has traveled 1000 meters
    locationManager.distanceFilter = 1000.0f;
    locationManager.delegate = self;
    locationManager.activityType = CLActivityTypeAutomotiveNavigation;

    [locationManager stopMonitoringSignificantLocationChanges];
    [locationManager startUpdatingLocation];
}


- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    // Check if running in background or not
    BOOL isInBackground = NO;
    if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
        isInBackground = YES;
    }

    if (isInBackground) {
        // If we're running in the background, run sendBackgroundLocationToServer
        [self sendBackgroundLocationToServer:[locations lastObject]];
    } else {
        // If we're not in the background wait till the GPS is accurate to send it to the server
        if ([[locations lastObject] horizontalAccuracy] < 100.0f) {
            [self sendDataToServer:[locations lastObject]];
        }
    }
}


-(void) sendBackgroundLocationToServer:(CLLocation *)location
{
    bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        [[UIApplication sharedApplication] endBackgroundTask:bgTask];
    }];

    // Send the data
    [self sendDataToServer:location];

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

-(void) sendDataToServer:(CLLocation *)newLocation
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        NSString *lat = [NSString stringWithFormat:@"%.8f", newLocation.coordinate.latitude];
        NSString *lng = [NSString stringWithFormat:@"%.8f", newLocation.coordinate.longitude];

        [APIConnection SaveMyPositionWitLat:lat withLng:lng];

    });
}

我需要每小时更新一次位置，或者如果用户更改位置超过1000米。我选择第二种方式来节省电池，但我的解决方案不能正常工作。

我非常感谢任何帮助，提前谢谢！

Answer 1

我不能确定这是否是你们所有人的问题，但我会做出以下改变：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
   // Moved to didFinishLaunching... you should not be recreating every time app
   // becomes active. You can check for locations key in the options Dictionary if
   // it is necessary to alter your setup based on background launch

   // Start location services
   locationManager = [[CLLocationManager alloc] init];
   locationManager.desiredAccuracy = kCLLocationAccuracyBest;

   // Only report to location manager if the user has traveled 1000 meters
   locationManager.distanceFilter = 1000.0f;
   locationManager.delegate = self;
   locationManager.activityType = CLActivityTypeAutomotiveNavigation;

   // Start monitoring significant locations here as default, will switch to
   // update locations on enter foreground
   [locationManager startMonitoringSignificantLocationChanges];

   // Hold in property to maintain reference
   self.locationManager = locationManager;
 }

在您的领导之后，这将是didBecomeActive方法中的所有内容（我会使用willEnterForeground代替）：

- (void)willEnterForeground:(UIApplication *)application
{
   [self.locationManager stopMonitoringSignificantLocationChanges];
   [self.locationManager startUpdatingLocation];
}

进入后台，仅返回重要的位置更改：

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    NSLog(@"Went to Background");
    // Need to stop regular updates first
    [self.locationManager stopUpdatingLocation];
    // Only monitor significant changes
    [self.locationManager startMonitoringSignificantLocationChanges];
}

在您的委托方法中，我建议您取消所有条件后台测试。我在后台任务标识符中包装，以防应用程序在后台或在完成之前进入后台。我也在全局线程上做出响应，所以我们不阻止UI（可选）：

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

    UIApplication *app = [UIApplication sharedApplication];
    __block UIBackgroundTaskIdentifier locationUpdateTaskID = [app beginBackgroundTaskWithExpirationHandler:^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (locationUpdateTaskID != UIBackgroundTaskInvalid) {
                [app endBackgroundTask:locationUpdateTaskID];
                locationUpdateTaskID = UIBackgroundTaskInvalid;
            }
        });
    }];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        // You might consider what to do here if you do not ever get a location accurate enough to pass the test.
       // Also consider comparing to previous report and verifying that it is indeed beyond your threshold distance and/or recency. You cannot count on the LM not to repeat.
       if ([[locations lastObject] horizontalAccuracy] < 100.0f) {
            [self sendDataToServer:[locations lastObject]];
       }

        // Close out task Identifier on main queue
        dispatch_async(dispatch_get_main_queue(), ^{
            if (locationUpdateTaskID != UIBackgroundTaskInvalid) {
                [app endBackgroundTask:locationUpdateTaskID];
                locationUpdateTaskID = UIBackgroundTaskInvalid;
            }
        });
    });
}

查看我的项目TTLocationHandler

在Github上了解更多使用Core Location的例子。

ios，startMonitoringSignificantLocationChanges - 有时会破坏监控

1 个答案: