我已经看到了一些这样的例子，但不确定如何实现它，（例如iPhone Compass GPS Direction）我是否需要在 (void)startup 中调用 calcBearingWithLatitude ？
我所要做的就是让指南针从记忆中拉出一个点并将该点用作它的“北”，可以这么说并指向它，不需要距离或类似的东西。
我现在的实现文件看起来像
@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