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POWeird behaviour in MKMapView - pins disappearing
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copied!<p>Within my app we have a screen with an MKMapView.</p> <p>This map shows pins for a bunch of Locations (location is a model defined within the app).</p> <p>When running in the simulator this works fine. However, when running this on a device the pins seem to disappear and re-appear almost each time the map is panned. Even slight touches and movements can cause the map to show and hide pins. </p> <p>The map isn't particularly busy, even when showing one pin it will show and hide it.</p> <p>Has anybody any idea why this might be happening? I've pasted my code below... It's a Rubymotion app so the code is in Ruby.</p> <h2>- UPDATE -</h2> <p>I've added the Objective C equivalent to this Ruby code below. Apologies if there are a couple of typos or idiomatic errors, it's been a while since I've written any OC.</p> <h2>- UPDATE 2 -</h2> <p>Watching the logger, I can see that <code>mapView:viewForAnnotation</code> is being called each time a map pin disappears/reappears.</p> <p>Also each time <code>mapView:regionDidChangeAnimated</code> I can see that the Object IDs for the annotations are the same - so I don't think they're being removed (which they shouldn't be)</p> <pre><code># ==================== # = MKMapKitDelegate = # ==================== # Don't react if the user has moved less than three meters USER_MOVE_THRESHOLD = 3 # The user location has changed def mapView(mapView, didUpdateUserLocation: newLocation) NSLog("mapView:didUpdateUserLocation") return unless userLocation coord = newLocation.coordinate newLocationAsCL = CLLocation.alloc.initWithCoordinate(coord, altitude: 1, horizontalAccuracy:1, verticalAccuracy: -1, timestamp: nil) meters = newLocationAsCL.distanceFromLocation(@lastUserCLLocation) # If user has moved less than 3m, return if meters > 0 and meters < USER_MOVE_THRESHOLD log "Distance was less than #{USER_MOVE_THRESHOLD} meters (#{meters}) - returning ***" return end # If the coord is the same as the previous user location if userLocation.coordinate.latitude == coord.latitude && userLocation.coordinate.longitude == coord.longitude log "User hasn't moved - returning ***" else log 'User has moved' end log "Did update user location: #{coord.latitude},#{coord.longitude}" if coord.latitude.to_f == 0.0 and coord.longitude.to_f == 0.0 log 'Invalid coordinate received - returning ***' else fetchLocationsFromAPI end end def mapView(mapView, regionDidChangeAnimated: animated) NSLog("mapView:regionDidChangeAnimated:#{animated}") # do nothing here yet... end # create map pins... def mapView(mapView, viewForAnnotation: annotation) log "mapView:viewForAnnotation: #{annotation.inspect}" if annotation.is_a?(Location) # If there's already an annotation we can use, use it! Otherwise create a new one annotationView = mapView.dequeueReusableAnnotationViewWithIdentifier(annotation.class.to_s) || begin annotationView = MKPinAnnotationView.alloc.initWithAnnotation(annotation, reuseIdentifier: annotation.class.to_s) annotationView.enabled = true annotationView.canShowCallout = true annotationView.animatesDrop = false annotationView.pinColor = MKPinAnnotationColorRed rightButton = UIButton.buttonWithType(UIButtonTypeDetailDisclosure) rightButton.addTarget(self, action: 'showLocationScreen:', forControlEvents: UIControlEventTouchUpInside) annotationView.rightCalloutAccessoryView = rightButton annotationView end annotationView.annotation = annotation annotationView.rightCalloutAccessoryView.tag = @mapLocations.index(annotation) return annotationView end end def mapView(mapViewm, didAddAnnotationViews: views) NSLog("mapView:didAddAnnotationViews - #{views}") # do nothing here yet... end </code></pre> <h2>Objective C</h2> <pre><code>#define kUserMoveThreshold 1 -(void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)newLocation { NSLog(@"mapView:didUpdateUserLocation") if (!userLocation) { return; } CLLocationCoordinate2D coord = newLocation.coordinate; CLLocation newLocationAsCL = [[CLLocation alloc] initWithCoordinate: coord altitude: 1 horizontalAccuracy: 1 verticalAccuracy: -1 timestamp: NULL]; CLLocationDistance meters = [newLocationAsCL distanceFromLocation: lastUserCLLocation]; // If user has moved less than 3m, return if (meters > 0 && meters < kUserMoveThreshold){ NSLog(@"Distance was less than %d meters (%d) - returning ***", kUserMoveThreshold, meters); return; } // If the coord is the same as the previous user location if (userLocation.coordinate.latitude == coord.latitude && userLocation.coordinate.longitude == coord.longitude){ NSLog(@"User hasn't moved - returning ***"); return; } else { NSLog(@"User has moved"); } NSLog(@"Did update user location: %f,%f", coord.latitude, coord.longitude); if (coord.latitude == 0.0 && coord.longitude == 0.0){ NSLog(@"Invalid coordinate received - returning ***"); } else { [self fetchLocationsFromAPI]; } } -(void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated { NSLog(@"mapView:regionDidChangeAnimated: %s", animated ? @"TRUE" : @"FALSE"); } -(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id < MKAnnotation >)annotation { NSLog(@"mapView:viewForAnnotation %s", annotation.description); if ([annotation isKindOfClass: [Location class]]){ // If there's already an annotation we can use, use it! Otherwise create a new one MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier: [annotation className]]; if (!annotationView){ annotationView = [[MKPinAnnotationView alloc] initWithAnnotation: annotation reuseIdentifier: [annotation className]]; [annotationView setEnabled: YES]; [annotationView setCanShowCallout: YES]; [annotationView setAnimatesDrop: NO]; [annotationView setPinColor: MKPinAnnotationColorRed]; UIButton *rightButton = [UIButton buttonWithType: UIButtonTypeDetailDisclosure]; [rightButton addTarget: self action: @selector(showLocationScreen:) forControlEvents: UIControlEventTouchUpInside]; [annotationView setRightCalloutAccessoryView: rightButton]; } [annotationView annotation: annotation]; [[annotationView rightCalloutAccessoryView] setTag: [mapLocations indexOfObject: annotation]]; return annotationView } } -(void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views { NSLog(@"mapView:didAddAnnotationViews %@", views) } </code></pre>

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