MKMapView - How to detect zoom vs drag event [closed] - ios

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How to detect zoom vs drag event on MKMapView.
I want to reload the map in case users want to drag/scroll map to new position. I don't want to reload the Map with zoom in/out event.

Answer 1

I found a solution :(. really simple
1. keep the previous zoom level.
2. in the regionDidChangeAnimated method, get new zoom level of Map and check it with the previous level.
this is my code.
#define MERCATOR_RADIUS 85445659.44705395
#define kVerySmallValue (0.000001)
- (BOOL)compare2Double:(double)first isEqualTo:(double)second {
if(fabs(first - second) < kVerySmallValue)
return YES;
else
return NO;
}
- (double)getZoomLevel
{
static double maxGoogleLevels = -1.0;
if (maxGoogleLevels < 0.0)
maxGoogleLevels = log2(MKMapSizeWorld.width / 256.0);
CLLocationDegrees longitudeDelta = self.mapView.region.span.longitudeDelta;
CGFloat mapWidthInPixels = self.mapView.bounds.size.width;
double zoomScale = longitudeDelta * MERCATOR_RADIUS * M_PI / (180.0 * mapWidthInPixels);
double zoomer = maxGoogleLevels - log2( zoomScale );
if ( zoomer < 0 ) zoomer = 0;
NSLog(#"zoom: %f",zoomer);
return zoomer;
}
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated {
double newZoom = [self getZoomLevel];
if ([self compareDouble:newZoom isEqualTo:zoomLevel]) {
NSLog(#"Drag");
}else{
zoomLevel = newZoom;
NSLog(#"Zoom");
}
}

Answer 2

You can find out through the below methods of PangestureRecognizer
- (void)viewDidLoad
{
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(dragMap:)];
panGesture.delegate = self;
[mapView addGestureRecognizer:panGesture];
}
-(void)dragMap:(UIPanGestureRecognizer*) gestureRecognizer
{
if(gestureRecognizer.state == UIGestureRecognizerStateBegan)
{
NSLog(#"The mapView Dragged");
}
}

Answer 3

I understand the problem.
Zoom or drag both the cases call regionWillChangeAnimated and regionDidChangeAnimated you want to differentiate between zoom and drag.
In MapViewControllerDelegate
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
// check mapView.centerCoordinate
// if mapView.centerCoordinate is equal previousCenterCoordinate {
// ZOOM
// } else {
//pinch gesture
//}
}
Update:
I thought my previous example will work. But it did not. This is my second attempt.
Add a method getZoomLevel
#define MERCATOR_OFFSET 268435456
#define MERCATOR_RADIUS 85445659.44705395
- (double) getZoomLevel
{
return 20.00 - log2(self.region.span.longitudeDelta * MERCATOR_RADIUS * M_PI / (180.0 * self.bounds.size.width));
}
In this method, self is mapView. I have a category of MKMapView so it is self in my case.
In MapViewControllerDelegate
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
// zoomLevel = [mapView getZoomLevel]; // or [self getZoomLevel] in your case
// if zoomLevel isEqual previousZoomLevel {
// did drag
// } else {
// did zoom
// previousZoomLevel = zoomLevel
//}
}