Comment faire pivoter une flèche de direction vers un emplacement particulier

Dans mon application j'ai une latitude-longitude de 1 correction de l'emplacement. Maintenant l'utilisateur avec l'iPhone peut se déplacer n'importe où et même lui faire tourner son appareil, la flèche (certains uiimageview) doit indiquer que la correction de l'emplacement de sorte que l'Utilisateur va obtenir la direction à cet endroit à chaque fois. J'ai essayé comme suit.

-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {

CLLocationCoordinate2D here =  newLocation.coordinate;
[self calculateUserAngle:here];
}


-(void) calculateUserAngle:(CLLocationCoordinate2D)user {
    NSLog(@"my destination is %f ; %f", fixlocLat, fixlocLon);
    degrees =  degrees + atan2(sin(fixlocLon-user.longitude)*cos(fixlocLat),cos(user.latitude)*sin(fixlocLat) - sin(user.latitude)*cos(fixlocLat)*cos(fixlocLon-user.longitude));
//get angle between user location and fix location
}

- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading 
{
    arrow.transform = CGAffineTransformMakeRotation((degrees-newHeading.trueHeading) * M_PI / 180);
}

mais le code ci-dessus va toujours tourner la flèche pour env. 2-3 degrés nord pour chaque emplacement.

Ma question ressemble à ce Débordement de Pile question.mais à l'aide de code à partir de ce lien, je suis mauvaise direction.
merci de m'aider sur ce point.

et aussi si une idée à l'aide de l'accéléromètre ou l'gyrodata sera utile pour moi.

merci à l'avance.

source d'informationauteur Dhawal

ce code peut vous aider à

-(void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading {
    //Use the true heading if it is valid. 
    CLLocationDirection direction = newHeading.magneticHeading;
    CGFloat radians = -direction / 180.0 * M_PI;

    self.strAccuracy = [NSString stringWithFormat:@"%.1fmi",newHeading.headingAccuracy];    
    [lblAccuracy setText:self.strAccuracy];

    //Rotate Bearing View
    [self rotateBearingView:bearingView radians:radians];

    //For Rotate Niddle
    CGFloat angle = RadiansToDegrees(radians);  
    [self setLatLonForDistanceAndAngle];
    [self rotateArrowView:arrowView degrees:(angle + fltAngle)];
}

-(void)rotateArrowView:(UIView *)view degrees:(CGFloat)degrees
{
    CGAffineTransform transform = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
    view.transform = transform;
}

-(void)setLatLonForDistanceAndAngle
{
    dblLat1 = DegreesToRadians(appDelegate.dblLatitude);
    dblLon1 = DegreesToRadians(appDelegate.dblLongitude);

    dblLat2 = DegreesToRadians(objClsProductSearch.dblLatitude);
    dblLon2 = DegreesToRadians(objClsProductSearch.dblLongitude);

    fltLat = dblLat2 - dblLat1;
    fltLon = dblLon2 - dblLon1;
}

-(float)getAngleFromLatLon
{
    //Calculate angle between two points taken from http://www.movable-type.co.uk/scripts    /latlong.html
    double y = sin(fltLon) * cos(dblLat2);
    double x = cos(dblLat1) * sin(dblLat2) - sin(dblLat1) * cos(dblLat2) * cos(dblLon2);
    CGFloat angle = RadiansToDegrees(atan2(y, x));
    return angle;
}

Cela fonctionne pour moi: pour faire pivoter une Flèche de Direction de l'emplacement particulier

-(void)viewDidLoad
{
    [super viewDidLoad]; 

    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self; 
    locationManager.desiredAccuracy = kCLLocationAccuracyBest; 
    locationManager.distanceFilter = kCLDistanceFilterNone;

}

-(void) calculateUserAngle:(CLLocationCoordinate2D)current {
    double x = 0, y = 0 , deg = 0,delLon = 0;

    delLon = fixLon - current.longitude;    
    y = sin(delLon) * cos(fixLat);
    x = cos(current.latitude) * sin(fixLat) - sin(current.latitude) * cos(fixLat) * cos(delLon);    
    deg = RADIANS_TO_DEGREES(atan2(y, x));    

    if(deg<0){      
        deg = -deg;
    } else {
        deg = 360 - deg;
    }    
    degrees = deg;
}


-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {

     CLLocationCoordinate2D here =  newLocation.coordinate;
     [self calculateUserAngle:here];
}


- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading 
{
    arrow.transform = CGAffineTransformMakeRotation((degrees-newHeading.trueHeading) * M_PI / 180);
}

-(void)viewDidLoad
{
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
locationManager.distanceFilter = kCLDistanceFilterNone;
[locationManager startUpdatingLocation];
[locationManager startUpdatingHeading];
}
-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
GeoAngle = [self setLatLonForDistanceAndAngle:newLocation];
}
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation *location=[locations lastObject];
GeoAngle = [self setLatLonForDistanceAndAngle:location];
}
-(float)setLatLonForDistanceAndAngle:(CLLocation *)userlocation
{
float lat1 = DegreesToRadians(userlocation.coordinate.latitude);
float lon1 = DegreesToRadians(userlocation.coordinate.longitude);
float lat2 = DegreesToRadians(Destination lattitude);
float lon2 = DegreesToRadians(Destination Longitude);
float dLon = lon2 - lon1;
float y = sin(dLon) * cos(lat2);
float x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon);
float radiansBearing = atan2(y, x);
if(radiansBearing < 0.0)
{
radiansBearing += 2*M_PI;
}
return radiansBearing;
}
-(void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading
{
float direction = -newHeading.trueHeading;
arrow.transform=CGAffineTransformMakeRotation((direction* M_PI / 180)+ GeoAngle);
}

Essayez cet exemple. Son en C# Xamarin tho 🙂
"double tête" est le CLHeading.MagneticHeading de la eventobject dans CLLocationManager.UpdatedHeading.

void UpdateCompass(Location origin, Location target, double heading)
{
var angle1 = GetAngleBetweenPoints(origin, target);
var angle2 = GetAngleFromHeading(heading);
var radian = Math.PI * (angle1 + angle2) / 180.0;
CompassArrow.Transform = CGAffineTransform.MakeRotation((nfloat)radian);
}
double GetAngleBetweenPoints(Location origin, Location target)
{
var n = 270 - (Math.Atan2(origin.Latitude - target.Latitude, origin.Longitude - target.Longitude)) * 180 / Math.PI;
return n % 360;
}
double GetAngleFromHeading(double heading)
{
var radians = -heading / 180.0 * Math.PI;
return radians * (180.0 / Math.PI);
}

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