How to stop multiple times method calling of didUpdateLocations() in ios

问题

This my code......

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

    location_updated = [locations lastObject];
    NSLog(@\"updated coordinate are %@\",location_updated);
    latitude1 = location_updated.coordinate.latitude;
    longitude1 = location_updated.coordinate.longitude;

    self.lblLat.text = [NSString stringWithFormat:@\"%f\",latitude1];
    self.lblLon.text = [NSString stringWithFormat:@\"%f\",longitude1];

    NSString *str = [NSString stringWithFormat:@\"https://maps.googleapis.com/maps/api/geocode/json?latlng=%f,%f&sensor=false\",latitude1,longitude1];
    url = [NSURL URLWithString:str];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    connection = [NSURLConnection connectionWithRequest:request delegate:self];
    if (connection)
    {
        webData1 = [[NSMutableData alloc]init];
    }
        GMSMarker *marker = [[GMSMarker alloc] init];
        marker.position = CLLocationCoordinate2DMake(latitude1,longitude1);
        marker.title = formattedAddress;
        marker.icon = [UIImage imageNamed:@\"m2.png\"];
        marker.map = mapView_;
        marker.draggable = YES;
 }

This method is call multiple times which i don\'t want.....

回答1:

Add some restriction there. For timespan between locations and accuracy

-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
 CLLocation *newLocation = locations.lastObject;

 NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];
 if (locationAge > 5.0) return;

 if (newLocation.horizontalAccuracy < 0) return;

// Needed to filter cached and too old locations
 //NSLog(@"Location updated to = %@", newLocation);
 CLLocation *loc1 = [[CLLocation alloc] initWithLatitude:_currentLocation.coordinate.latitude longitude:_currentLocation.coordinate.longitude];
 CLLocation *loc2 = [[CLLocation alloc] initWithLatitude:newLocation.coordinate.latitude longitude:newLocation.coordinate.longitude];
 double distance = [loc1 distanceFromLocation:loc2];


 if(distance > 20)
 {    
     _currentLocation = newLocation;

     //significant location update

 }

//location updated

}

回答2:

While allocating your LocationManager object you can set the distanceFilter property of the LocationManager. Distance filter property is a CLLocationDistance value which can be set to notify the location manager about the distance moved in meters. You can set the distance filter as follows:

LocationManager *locationManger = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = 100.0; // Will notify the LocationManager every 100 meters
locationManager.desiredAccuracy = kCLLocationAccuracyBest;

回答3:

The easiest way:

-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray<CLLocation *> *)locations
{
   [manager stopUpdatingLocation];
    manager.delegate = nil;

   //...... do something

}

The manager can't find your didUpdateLocations method without the delegate reference :-D

But don't forget to set it again before using startUpdatingLocation

回答4:

I have similar situation. You can use dispatch_once:

static dispatch_once_t predicate;

- (void)update
{
    if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusNotDetermined &&
        [_locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)]) {
        [_locationManager requestWhenInUseAuthorization];
    }

    _locationManager.delegate = self;
    _locationManager.distanceFilter = kCLDistanceFilterNone;
    _locationManager.desiredAccuracy = kCLLocationAccuracyBest;

    predicate = 0;
    [_locationManager startUpdatingLocation];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
    [manager stopUpdatingLocation];
    manager = nil;

    dispatch_once(&predicate, ^{
        //your code here
    });
}

回答5:

You can use a static variable to store the latest location timestamp and then compare it to the newest one, like this:

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    [manager stopUpdatingLocation];
    static NSDate *previousLocationTimestamp;

    CLLocation *location = [locations lastObject];
    if (previousLocationTimestamp && [location.timestamp timeIntervalSinceDate:previousLocationTimestamp] < 2.0) {
        NSLog(@"didUpdateLocations GIVE UP");
        return;
    }
    previousLocationTimestamp = location.timestamp;

    NSLog(@"didUpdateLocations GOOD");

    // Do your code here
}

回答6:

Write this method when ever you want to stop updating location manager

[locationManager stopUpdatingLocation];

回答7:

for the time constraint, i did not understand code from accepted answer, posting a different approach. as Rob points out "When you first start location services, you may see it called multiple times". the code below acts on the first location, and ignores the updated locations for first 120 seconds. it is one way to address orginal question "How to stop multiple times method calling of didUpdateLocations".

in .h file:

@property(strong,nonatomic) CLLocation* firstLocation;

in .m file:

// is this the first location?
    CLLocation* newLocation = locations.lastObject;
    if (self.firstLocation) {
        // app already has a location
        NSTimeInterval locationAge = [newLocation.timestamp timeIntervalSinceDate:self.firstLocation.timestamp];
        NSLog(@"locationAge: %f",locationAge);
        if (locationAge < 120.0) {  // 120 is in seconds or milliseconds?
            return;
        }
    } else {
        self.firstLocation = newLocation;
    }

    // do something with location

回答8:

You could set a flag (Bool). When you instantiate your locationsManager set flag = true then when locationManager:didUpdateLocations returns inside a code block that you want to run only once set flag = false. This way it will only be run the once.

 if flag == true {
     flag = false
    ...some code probably network call you only want to run the once 
    }

locations manager will be called multiple times but the code you want to execute only once, and I think that is what you are trying to achieve?

回答9:

locationManager.startUpdatingLocation() fetch location continuously and didUpdateLocations method calls several times, Just set the value for locationManager.distanceFilter value before calling locationManager.startUpdatingLocation().

As I set 200 meters(you can change as your requirement) working fine

    locationManager = CLLocationManager()
    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
    locationManager.distanceFilter = 200
    locationManager.requestWhenInUseAuthorization()
    locationManager.startUpdatingLocation()

回答10:

you can write : [manager stopUpdatingLocation]; manager = nil; in didupdatelocation delegate

来源：https://stackoverflow.com/questions/22292835/how-to-stop-multiple-times-method-calling-of-didupdatelocations-in-ios

标签

ios

iphone

cllocationmanager

cllocation