iphone - 无需更改即可调用函数“didUpdateToLocation”

Question

我以这种方式初始化locationManager:

if (!self.locManager) 
{
    self.locManager = [[CLLocationManager alloc] init];
    self.locManager.delegate = self;
    [locManager startMonitoringSignificantLocationChanges];
}

我的设备没有移动，并且每次仍在调用“didUpdateToLocation”。
可能是什么问题？
谢谢

Answer 1

didUpdateToLocation可能由于多种原因而更新，一种解决此问题的好策略是根据时间戳逐渐过滤结果，然后根据所需的准确性进行过滤。

苹果在LocateMe sample app中提供了一个很好的例子:

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    // test the age of the location measurement to determine if the measurement is cached
    // in most cases you will not want to rely on cached measurements
    NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];
    if (locationAge > 5.0) return;

    // test that the horizontal accuracy does not indicate an invalid measurement
    if (newLocation.horizontalAccuracy < 0) return;

    // test the measurement to see if it is more accurate than the previous measurement
    if (self.bestEffortAtLocation == nil || self.bestEffortAtLocation.horizontalAccuracy > newLocation.horizontalAccuracy)
    {
        // store the location as the "best effort"
        self.bestEffortAtLocation = newLocation;

        // test the measurement to see if it meets the desired accuracy
        //
        // IMPORTANT!!! kCLLocationAccuracyBest should not be used for comparison with location coordinate or altitidue 
        // accuracy because it is a negative value. Instead, compare against some predetermined "real" measure of 
        // acceptable accuracy, or depend on the timeout to stop updating. This sample depends on the timeout.
        //
        if (newLocation.horizontalAccuracy <= locationManager.desiredAccuracy) {
            // we have a measurement that meets our requirements, so we can stop updating the location
            // 
            // IMPORTANT!!! Minimize power usage by stopping the location manager as soon as possible.
            //
            [self stopUpdatingLocation:NSLocalizedString(@"Acquired Location", @"Acquired Location")];
        }
    }
}