如何在 ios 中停止多次调用 didUpdateLocations() 方法

Question

这是我的代码......

 -(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;
 }

这个方法被多次调用，我不想要.....

Answer 1

在分配LocationManager 对象时，您可以设置LocationManager 的distanceFilter 属性。距离过滤器属性是一个CLLocationDistance 值，可以设置它以通知位置管理器移动的距离（以米为单位）。您可以按如下方式设置距离过滤器：

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

Answer 2

在那里添加一些限制。对于位置和准确性之间的时间跨度

-(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

}

Answer 3

最简单的方法：

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

   //...... do something

}

没有 delegate 参考，经理找不到您的 didUpdateLocations 方法：-D

但不要忘记在使用 startUpdatingLocation

之前再次设置它

Answer 4

我也有类似的情况。您可以使用 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
    });
}

Answer 5

locationManager.startUpdatingLocation() 连续获取位置，didUpdateLocations 方法调用多次， 只需在调用 locationManager.startUpdatingLocation() 之前设置 locationManager.distanceFilter 的值即可。

因为我设置了 200 米（您可以根据需要更改）工作正常

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

Answer 6

您可以使用静态变量来存储最新的位置时间戳，然后将其与最新的进行比较，如下所示：

- (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
}

Answer 7

当您想停止更新位置管理器时编写此方法

[locationManager stopUpdatingLocation];

Answer 8

由于时间限制，我不理解已接受答案中的代码，因此发布了不同的方法。正如 Rob 指出的那样“当您第一次启动定位服务时，您可能会看到它被多次调用”。下面的代码作用于第一个位置，并在前 120 秒内忽略更新的位置。这是解决原始问题“如何停止对 didUpdateLocations 的多次方法调用”的一种方法。

在 .h 文件中：

@property(strong,nonatomic) CLLocation* firstLocation;

在 .m 文件中：

// 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

Answer 9

您可以设置一个标志 (Bool)。当您实例化您的位置管理器设置标志 = true 时，位置管理器：didUpdateLocations 在代码块内返回 您只想运行一次设置标志 = false。这样它只会运行一次。

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

locations manager 将被多次调用，但您只想执行一次代码，我认为这就是您想要实现的目标？

Answer 10

你可以写： [经理停止更新位置]； 经理=无； 在 didupdatelocation 委托中