如何将方向箭头旋转到特定位置

Question

在我的应用程序中,我有一个经度为1的固定位置.现在,使用iPhone设备的用户可以移动到任何地方,甚至他可以旋转他的设备,箭头(一些uiimageview)应该指向该修复位置,这样用户每次都会获得指向该位置的方向.我尝试如下.

-(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);
}

但上面的代码总是将箭头旋转到约.每个位置北2-3度.

我的问题类似于这个Stack Overflow问题.但是使用此链接中的代码我的方向错误.请帮帮我.

如果任何使用加速度计或gyrodata的想法对我有帮助.

提前.

Answer 1

这适用于我:将方向箭头旋转到特定位置

-(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);
}

Answer 2

这段代码可以帮到你

-(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;
}