Iphone 使用指南针指向实际坐标位置，而不是仅仅指向北方

我已经看到了一些这样的例子，但不确定具体如何实现它，（例如）在（void）startup中是否需要调用calcBearingWithLatitude

我所要做的就是让指南针从记忆中提取一个点，并用这个点作为它的“北”，可以这样说，并指向它，不需要距离之类的东西

到现在为止，我的实现文件如下所示

@implementation TrackerViewController

@synthesize locationManager; 
@synthesize compass; 
@synthesize headingLabel;

- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];

if ([CLLocationManager headingAvailable]) {

} else {
    [[[[UIAlertView alloc] initWithTitle:@"Error" 
                                 message:@"Device doesn't support heading updates" 
                                delegate:nil 
                       cancelButtonTitle:@"OK" 
                       otherButtonTitles:nil] autorelease] show];   
}
}

- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading {
double heading = [newHeading magneticHeading] * M_PI / 180.0;
self.compass.transform = CGAffineTransformMakeRotation(-heading);
self.headingLabel.text = [NSString stringWithFormat:@"%d°", (int)[newHeading magneticHeading]];
NSLog(@"%d", (int)[newHeading magneticHeading]);
}


- (void)locationManager:(CLLocationManager *)manager 
   didFailWithError:(NSError *)error {

//  NSLog(@"Error!");

if (error.code == kCLErrorDenied) {
    [[[[UIAlertView alloc] initWithTitle:@"Error" 
                                 message:@"User didn't allow heading updates" 
                                delegate:nil 
                       cancelButtonTitle:@"OK" 
                       otherButtonTitles:nil] autorelease] show];
    [self.locationManager stopUpdatingHeading];
}
}

 - (void)viewDidLoad {
 locationManager=[[CLLocationManager alloc] init];
 locationManager.desiredAccuracy = kCLLocationAccuracyBest;
 locationManager.delegate=self;
 //Start the compass updates.
 [locationManager startUpdatingHeading];
 [super viewDidLoad];
 }

- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.
}

- (void)dealloc {
self.locationManager = nil;
self.compass = nil;
self.headingLabel = nil;
[super dealloc];
}

@end

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我会找到坐标A到坐标B之间的方位角，然后使用该方位角作为罗盘方位角从坐标A到坐标B的偏移量

这里有两个用于查找坐标方向的链接

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如果希望指南针方位在移动时更新，使其始终指向坐标B，则可能需要在获得新方位或位置时重新计算

你能为指南针创建一个自定义航向吗？