MKMapView

Question

如何检测 MKMapView 上的缩放事件和拖动事件。

我想重新加载地图以防用户drag/scroll映射到新位置。我不想使用缩放 in/out 事件重新加载地图。

Answer 1

您可以通过PangestureRecognizer的以下方法进行查找

- (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 2

我明白了。

缩放或拖动这两种情况调用 regionWillChangeAnimated 和 regionDidChangeAnimated 您想要区分缩放和拖动。

在MapViewControllerDelegate

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated 
{
    // check mapView.centerCoordinate
    // if mapView.centerCoordinate is equal previousCenterCoordinate {
        // ZOOM
    // } else {
        //pinch gesture
    //}
}

更新：

我认为我之前的示例会起作用。但事实并非如此。这是我的第二次尝试。

添加方法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));
}

在这个方法中，self 是 mapView。我的类别是 MKMapView，所以在我的例子中是 self。

在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
    //}
}

Answer 3

我找到了一个解决方案:(。真的很简单 1.保持之前的缩放级别。 2. 在 regionDidChangeAnimated 方法中，获取地图的新缩放级别并与之前的级别进行检查。这是我的代码。

#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");
    }
    
}

MKMapView - 如何检测缩放与拖动事件

MKMapView - How to detect zoom vs drag event

objective-c

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