Detect zoom on GMSMapView (iOS) - ios

Question

How can I find if the user zoomed in/out on my mapView (GMSMapView)?
I want to do that if the zoom is bigger than 14 all the markers on the map will disappear and if it's smaller all the markers will reload.
How can I do that?
Thanks!

Answer 1

The below code assumes that the view controller has a property of "markerArray" which holds all of the markers.
-(void)mapView:(GMSMapView *)mapView didChangeCameraPosition:(GMSCameraPosition*)position {
int zoom= mapView.camera.zoom;
if (zoom < 14) {
[mapView_ clear];
}
else{
[self displayAllMarkers];
}
}
-(void) displayAllMarkers{
for (BarObject *barMarker in markerArray){
GMSMarker *marker = [[GMSMarker alloc] init];
marker.position = barMarker.location; //
marker.icon = [GMSMarker markerImageWithColor:[UIColor blackColor]];
marker.map = mapView_;
}
}

Answer 2

I also searched for this answer over the summer, and here is what I found and ended up doing:
Create a category on MKMapView:
I named it MKMapView+ZoomLevel
.h
// MKMapView+ZoomLevel.h
#import <MapKit/MapKit.h>
#interface MKMapView (ZoomLevel)
- (int)currentZoomLevel;
#end
.m
// MKMapView+ZoomLevel.m
#import "MKMapView+ZoomLevel.h"
#define MERCATOR_OFFSET 268435456
#define MERCATOR_RADIUS 85445659.44705395
#define MAX_GOOGLE_LEVELS 20
#implementation MKMapView (ZoomLevel)
- (int)currentZoomLevel
{
CLLocationDegrees longitudeDelta = self.region.span.longitudeDelta;
CGFloat mapWidthInPixels = self.bounds.size.width*2;//2 is for retina display
double zoomScale = longitudeDelta * MERCATOR_RADIUS * M_PI / (180.0 * mapWidthInPixels);
double zoomer = MAX_GOOGLE_LEVELS - log2( zoomScale );
if ( zoomer < 0 ) zoomer = 0;
zoomer = round(zoomer);
return (int)zoomer;
}
#end
Then in your view controller:
#import "MKMapView+ZoomLevel.h
// insert logic here
double zoomLevel = [self.mapView currentZoomLevel];
if (zoomLevel > 14 ) {
// add code to hide or resize your annotations
for (id<MKAnnotation> annotation in self.mapView.annotations) {
if (![annotation isKindOfClass:[MKUserLocation class]]) {
[self.mapView removeAnnotation:annotation];
}
}
}