Question

在CLLocationManagerDelegate中，该方法何时被调用：locationManager：didUpdateToLocation：fromLocation：

你可以解释更多的细节，如果可能的话，你可以用例子来解释吗？非常感谢

如果我当前的位置正在改变（例如，我在火车上），是否会调用此方法？如果是，可以调用多少次或多少次？
如果我留在一个地方而不动，是否会调用此方法？如果是，可以调用多少次或多少次？

Answer 1

只要您的iOS设备移过您设置的距离过滤器，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。

这样的代码示例是找到坐标，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

对于第一个调用此方法，频率取决于速度。

如果不改变您的位置，则不会调用此方法。

您的位置改变此方法的时间将会调用。

CLLocationManagerDelegate，该方法何时被调用：locationManager：didUpdateToLocation：fromLocation：

2 个答案: