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copied!<p>You can ;) To do so, you need to implement this method :</p> <pre><code>- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation </code></pre> <p>In this one you will have to create a instance of a subclass of MKAnnotationView only for the user location case of annotation like:</p> <pre><code>- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation { if ([annotation isKindOfClass:[MKUserLocation class]]) { if (userView == nil) { userView=[[[UserLocationView alloc] initWithAnnotation:annotation reuseIdentifier:@"user"] autorelease]; } [self addObserver:userView forKeyPath:@"userHeading" options:NSKeyValueObservingOptionNew context:NULL] ; return userView ; } return nil; } </code></pre> <p>Note the KVO statement to let your custom MKAnnotationView that the value has changed in your MKAnnotationView subclass you need to override drawRect; like that for example</p> <pre><code>- (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); NSAssert(context !=nil, @"Context was nil") ; CGContextSetRGBStrokeColor (context,1.0f,0.0f,0.0f,1.0f) ; CGContextSetLineWidth(context, 2.0f); CGContextMoveToPoint(context, 0, 15); CGContextAddLineToPoint(context, 30, 15); CGContextMoveToPoint(context, 15,0); CGContextAddLineToPoint(context, 15, 30); CGContextStrokePath(context); CGContextSetLineWidth(context, 4.0f); CGContextAddArc (context,15,15,13,0,6.28,0); CGContextStrokePath(context); hdg = radians([self heading]); dx = self.frame.size.width / 2 ; dy = self.frame.size.height/ 2 ; if (hdg < M_PI) { y = (cos(hdg) * dy ) - dy ; x = (sin(hdg) * dx ) + dx ; } else { y = (cos(hdg) * dy ) + dy ; x = (sin(hdg) * dx ) + dx ; } // NSLog(@"Heading:%3f Hdg:%3f X:%3f Y:%3f", heading, hdg, x, y) ; CGContextSetRGBStrokeColor (context,1.0f,0.0f,1.0f,1.0f) ; CGContextSetLineWidth(context, 2.0f); CGContextMoveToPoint(context, dx,dy); CGContextAddLineToPoint(context, x, y); CGContextStrokePath(context); } </code></pre> <p>This draws a red reticle with a purple line showing the heading (in my sample the course is bugged because i am just weak in trigonometry ;) but it draws :) </p> <p>You of course need to handle the KVO notification like:</p> <pre><code>-(void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { [self setHeading: [[change objectForKey:NSKeyValueChangeNewKey]doubleValue]] ; [self setNeedsDisplay] ; NSLog(@"Heading is %f", [self heading]); } </code></pre> <p>the <code>-setNeedsDisplay</code> will trigger the redraw.</p> <p>Make sure that you custom view has a non-zero rect frame, and do NOT set an image to it.</p>

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