CLLocationManagerDelegate，什么时候调用该方法：locationManager:didUpdateToLocation:fromLocation:

Question

在 CLLocationManagerDelegate 中，何时调用该方法： locationManager:didUpdateToLocation:fromLocation:

你能解释更多细节吗？如果可能的话，你能用例子解释一下吗？非常感谢

1. 如果我当前的位置发生变化（例如，我在火车上），是否会调用此方法？如果是，调用多少次或频率？

2. 如果我呆在一个地方不动，这个方法会被调用吗？如果是，调用了多少次或者频率？

Answer 1

每当您的 iOS 设备超出您设置的距离过滤器时，就会调用此方法。例如，如果将其设置为

[self.locationManager setDistanceFilter:kCLDistanceFilterNone];

每次移动设备时都会调用该方法。

一个代码示例是查找坐标，然后将这些值分配给标签

- (void)viewDidLoad{
[super viewDidLoad];
altitudeLabel.text = @"0 ft";
ftOrM = YES;
// Note: we are using Core Location directly to get the user location updates.
// We could normally use MKMapView's user location update delegation but this does not work in
// the background.  Plus we want "kCLLocationAccuracyBestForNavigation" which gives us a better accuracy.
//
self.locationManager = [[[CLLocationManager alloc] init] autorelease];
self.locationManager.delegate = self; // Tells the location manager to send updates to this object
[self.locationManager setDesiredAccuracy:kCLLocationAccuracyBestForNavigation];
[self.locationManager setDistanceFilter:kCLDistanceFilterNone];

[self.locationManager startUpdatingLocation];

}

-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:   (CLLocation*)newLocation fromLocation:(CLLocation *)oldLocation { 
tLatitude  = [NSString stringWithFormat:@"%3.5f", newLocation.coordinate.latitude]; 
tLongitude = [NSString stringWithFormat:@"%3.5f", newLocation.coordinate.longitude];
/*  the following returns 0 */
float distanceMeters;
float distanceFeet;
if (ftOrM == YES) {
    distanceMeters = newLocation.altitude;
    distanceFeet = distanceMeters * 3.2808399;
    tAltitude  = [NSString stringWithFormat:@"%.02f ft",    distanceFeet];
     altitudeLabel.text = tAltitude;
}
else {
tAltitude  = [NSString stringWithFormat:@"%.02f m",    newLocation.altitude];
NSLog(@"Altitude:");
NSLog(@"%@", tAltitude);
altitudeLabel.text = tAltitude;
NSLog(@"Altitude:");
NSLog(@"%@", tAltitude);
}
//[manager stopUpdatingLocation];
}

Answer 2

对于第一个方法，将调用此方法，频率取决于速度。

如果不更改您的位置，则不会调用此方法。

以及你的位置发生变化多少时间这个方法就会调用。