问在MKMapView映射模式下设置MKMapCamera时的怪异MKUserTrackingModeFollowWithHeading行为

EN

#import "CCViewController.h"

@interface CCViewController ()
@end

@implementation CCViewController

- (void)viewDidLoad{
    [super viewDidLoad];
}

- (void)setUpMap{
    [self.mapView setShowsUserLocation: YES];
}

- (void)viewDidAppear:(BOOL)animated{
    [self setUpMap];
}

- (IBAction)mapModeSwitchClicked:(id)sender {
    MKMapCamera *newCamera = [MKMapCamera camera];
    newCamera.centerCoordinate = self.mapView.camera.centerCoordinate;
    newCamera.heading = self.mapView.camera.heading;
    newCamera.altitude = self.mapView.camera.altitude;

    if(!self.mapView.camera.pitch){
        newCamera.pitch = 50;
        self.mapModeSwitch.title = @"2D";
    }
    else{
        newCamera.pitch = 0;
        self.mapModeSwitch.title = @"3D";
    }

    [self.mapView setCamera:newCamera animated:YES];
}

- (IBAction)locateMeButtonClicked:(id)sender {

        if(self.mapView.userTrackingMode != MKUserTrackingModeFollowWithHeading)
            [self.mapView setUserTrackingMode:MKUserTrackingModeFollowWithHeading animated:YES];
        else
            [self.mapView setUserTrackingMode:MKUserTrackingModeNone animated:YES];
}

- (void)zoomMapWithZoomFactor:(double)factor{
    MKMapCamera *newCamera = [MKMapCamera camera];
    newCamera.pitch = self.mapView.camera.pitch;
    newCamera.heading = self.mapView.camera.heading;
    newCamera.altitude = self.mapView.camera.altitude * factor;
    newCamera.centerCoordinate = self.mapView.camera.centerCoordinate;

    [self.mapView setCamera:newCamera animated:YES];
}

- (IBAction)zoomInClicked:(id)sender {
    [self zoomMapWithZoomFactor: 0.5];
}

- (IBAction)zoomOutClicked:(id)sender {
     [self zoomMapWithZoomFactor: 2];
}


@end