Resizing an MKAnnotationView image When are the maps zooming in and out?

Question

What i have

I have about 150 MKAnnotationViews on the map. Each MKAnnotationView has an image that replaces the default output.

What is happening now

As the map draws closer, MKAnnotationViews get smaller, and vice versa they get smaller.

What i want to happen

Well, I want it to be the other way around. Since when the map is small, I want MKAnnotationViews to be smaller so that the user can see them all, and when it scales, I want them to be larger.

What code do I still have

I know how to get a zoom change, and I know that I can get "pMapView.region.span.latitudeDelta" as a reference for the magnification amount. and I know that I can change annotationView.frame.

-(void)mapView:(MKMapView *)pMapView regionDidChangeAnimated:(BOOL)animated{
    NSLog(@"mapView.region.span.latitudeDelta = %f",pMapView.region.span.latitudeDelta);
    for (id <MKAnnotation> annotation in pMapView.annotations) {
        MKAnnotationView *annotationView  = [pMapView viewForAnnotation: annotation];
    }
}

- , ?

Answer 1

MKMapView - (, ) (, ) , . . , , -, , .

, , :

• -(void)mapView:(MKMapView *)pMapView regionDidChangeAnimated:(BOOL)animated MKMapViewDelegate Protocol Reference - .
• UIPinchGestureRecognizer MKMapView .

№1 - mapView:regionDidChangeAnimated: , - , , . , .

№ 2 - a UIPinchGestureRecognizer MKMapView, . , . , .

:

- (void)handleGesture;
- (void)handleGesture:(UIGestureRecognizer *)gestureRecognizer;

, . . : "UIMapView: UIPinchGestureRecognizer " . , shouldRecognizeSimultaneouslyWithGestureRecognizer: YES.

:

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
    [super viewDidLoad];

    self.mapView.mapType = MKMapTypeStandard;   // also MKMapTypeSatellite or MKMapTypeHybrid

    // Add a pinch gesture recognizer
    UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinchGesture:)];
    pinchRecognizer.delegate = self;
    [self.mapView addGestureRecognizer:pinchRecognizer];
    [pinchRecognizer release];
}

#pragma mark -
#pragma mark UIPinchGestureRecognizer

- (void)handlePinchGesture:(UIPinchGestureRecognizer *)pinchRecognizer {
    if (pinchRecognizer.state != UIGestureRecognizerStateChanged) {
        return;
    }

    MKMapView *aMapView = (MKMapView *)pinchRecognizer.view;

    for (id <MKAnnotation>annotation in aMapView.annotations) {
        // if it the user location, just return nil.
        if ([annotation isKindOfClass:[MKUserLocation class]])
            return;

        // handle our custom annotations
        //
        if ([annotation isKindOfClass:[MKPointAnnotation class]])
        {
            // try to retrieve an existing pin view first
            MKAnnotationView *pinView = [aMapView viewForAnnotation:annotation];
            //Format the pin view
            [self formatAnnotationView:pinView forMapView:aMapView];
        }
    }    
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    return YES;
}

, . MKMapView.

• . , . - .
• - Trevor Harmon UIImage, , .

:

- (void)formatAnnotationView:(MKAnnotationView *)pinView forMapView:(MKMapView *)aMapView {
    if (pinView)
    {
        double zoomLevel = [aMapView zoomLevel];
        double scale = -1 * sqrt((double)(1 - pow((zoomLevel/20.0), 2.0))) + 1.1; // This is a circular scale function where at zoom level 0 scale is 0.1 and at zoom level 20 scale is 1.1

        // Option #1
        pinView.transform = CGAffineTransformMakeScale(scale, scale);

        // Option #2
        UIImage *pinImage = [UIImage imageNamed:@"YOUR_IMAGE_NAME_HERE"];
        pinView.image = [pinImage resizedImage:CGSizeMake(pinImage.size.width * scale, pinImage.size.height * scale) interpolationQuality:kCGInterpolationHigh];
    }
}

, .

Answer 2

... -.

, Funktional. ... iOS5 ! iOS6, , , .

, , /, iOS. . , .

• mkannotation pin.png( 20x20)

• (18x18, 16x16, 14x14, 12x12, 10x10), pin-5.png, pin-4.png, pin-3.png, pin-2.png, pin-1.png.

• AnnotationView

  NSString* imageName = 
      [NSString stringWithFormat:@"%@%@.png", 
      [imageName substringToIndex:[imageName length]-4 ], 
      [self getImageLevel]];
  

• ,

  UIImage * pinImage = [UIImage imageNamed: @ "YOUR_IMAGE_NAME_HERE" ];

  UIImage * pinImage = [[UIImage alloc] initWithContentsOfFile: imageName];

• -(NSString *)getImageLevel{
  
  NSString* output;
  
  double zoomLevel = [self getZoomLevel:_mapview];
  
  
  if(zoomLevel >= 19.0)
      output = @"";
  else if(zoomLevel < 19.0 && zoomLevel >= 18.0)
      output = @"-5";
  else if(zoomLevel < 18.0 && zoomLevel >= 17.0)
      output = @"-4";
  else if(zoomLevel < 17.0 && zoomLevel >= 16.0)
      output = @"-3";
  else if(zoomLevel < 16.0 && zoomLevel >= 15.0)
      output = @"-2";
  else 
      output = @"-1";
  
  return output;}
  

, .

Answer 3

.

Answer 4

In Swift 3, this worked for me. My image was 100% at level 19, so 1/19 gives me .5263158, which is my linear scale:

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {    
  if annotation is MKUserLocation {
    return nil
  }

  let mkView = MKAnnotationView(annotation: annotation, reuseIdentifier: "mkView")
  mkView.image = UIImage(named: "Foo")
  formatAnnotation(pinView: mkView, forMapView: mapView)
  return mkView;
}

func formatAnnotation(pinView: MKAnnotationView, forMapView: MKMapView) {
  let zoomLevel = forMapView.getZoomLevel()
  let scale = 0.05263158 * zoomLevel //Modify to whatever scale you need.
  pinView.transform = CGAffineTransform(scaleX: CGFloat(scale), y: CGFloat(scale))
}

Answer 5

@ Functional answer in Swift 3:

class MapViewController: UIViewController: UIGestureRecognizerDelegate {

    @IBOutlet weak var mapView: MKMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // You can also add this gesture recognizer and set the delegate via storyboard
        let pinchGR = UIPinchGestureRecognizer(target: self, action: #selector(handlePinchGesture))
        pinchGR.delegate = self
        self.mapView.addGestureRecognizer(pinchGR)
    }

    // link as @IBAction when added via storyboard
    func handlePinchGesture(_ sender: UIPinchGestureRecognizer) {
        if sender.state == .ended {
            for annotation in mapView.annotations {
                if annotation is MKUserLocation {
                    continue
                }
                guard let annotationView = self.mapView.view(for: annotation) else { continue }
                let scale = -1 * sqrt(1 - pow(mapView.zoomLevel / 20, 2.0)) + 1.4
                annotationView.transform = CGAffineTransform(scaleX: CGFloat(scale), y: CGFloat(scale))
            }
        }
    }

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }
}

extension MKMapView {
    var zoomLevel: Double {
        return log2(360 * ((Double(self.frame.size.width) / 256) / self.region.span.longitudeDelta)) - 1
    }
}