ios - 核心位置会在背景出现时给出旧位置

Question

我在VC中有一个CoreLocation管理器，当用户按下“获取方向”按钮时，我启动了位置管理器，然后应用打开了带有当前位置和一些预定义目标位置的google map方向。

这是我的问题，如果应用程序不是处于后台状态，当前位置几乎总是为true，但是如果应用程序在同一VC中从后台调用并且用户再次按下“获取方向”按钮，则当前位置通常显示旧位置。简而言之，我在进行多任务处理时遇到麻烦，并且获取位置的时间戳无法解决我的问题。

IBAction:

   if ( self.locationManager ) {
        [_locationManager release];
        self.locationManager = nil;
    }
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.delegate = self;
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    self.locationManager.distanceFilter = kCLDistanceFilterNone;

    self.locationTimer = [NSTimer scheduledTimerWithTimeInterval:LOCATION_TIMER target:self selector:@selector(stopUpdatingLocationTimer) userInfo:nil repeats:NO];
    HUD = [MBProgressHUD showHUDAddedTo:self.navigationController.view animated:YES];
    [self.locationManager startUpdatingLocation]; 

核心位置代表:

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {


NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];
NSLog(@"%f",locationAge);
if (locationAge > 3.0) 
    return;

if (newLocation.horizontalAccuracy < 0) 
    return;

if ( self.currentLocation == nil || self.currentLocation.horizontalAccuracy > newLocation.horizontalAccuracy ) {

    self.currentLocation = newLocation;

    if (self.currentLocation.horizontalAccuracy <= self.locationManager.desiredAccuracy) {

        [self stopUpdatingLocations:YES];

    }

}

}

Answer 1

在您的示例中，locationAge是自timestamp的newLocation以来的秒数的否定表示。这意味着locationAge永远不会大于3，并且您实际上是在让每次更新都过筛。

像这样设置locationAge:

NSTimeInterval locationAge = [newLocation.timestamp timeIntervalSinceNow];