我正在编写以下代码,
- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated {
mapRegion = mapView.region; //MKCoordinateRegion myRegion in .h
}
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated {
MKCoordinateRegion newRegion = mapView.region;
if (mapRegion.span.latitudeDelta != newRegion.span.latitudeDelta ||
mapRegion.span.longitudeDelta != newRegion.span.longitudeDelta){
NSLog(@"The zoom has changed");
}
}
我想在用户放大或缩小MKMapView时做一些操作,我该怎么做但是通过应用上面的代码,如果条件将执行使用将不会放大/缩小但只是将改变地图?
答案 0 :(得分:22)
将MKMapView+ZoomLevel.h
设为
#import <MapKit/MapKit.h>
@interface MKMapView (ZoomLevel)
- (void)setCenterCoordinate:(CLLocationCoordinate2D)centerCoordinate
zoomLevel:(double)zoomLevel
animated:(BOOL)animated;
@end
将MKMapView+ZoomLevel.m
设为
#import "MKMapView+ZoomLevel.h"
#define MERCATOR_OFFSET 268435456
#define MERCATOR_RADIUS 85445659.44705395
@implementation MKMapView (ZoomLevel)
#pragma mark -
#pragma mark Map conversion methods
- (double)longitudeToPixelSpaceX:(double)longitude
{
return round(MERCATOR_OFFSET + MERCATOR_RADIUS * longitude * M_PI / 180.0);
}
- (double)latitudeToPixelSpaceY:(double)latitude
{
return round(MERCATOR_OFFSET - MERCATOR_RADIUS * logf((1 + sinf(latitude * M_PI / 180.0)) / (1 - sinf(latitude * M_PI / 180.0))) / 2.0);
}
- (double)pixelSpaceXToLongitude:(double)pixelX
{
return ((round(pixelX) - MERCATOR_OFFSET) / MERCATOR_RADIUS) * 180.0 / M_PI;
}
- (double)pixelSpaceYToLatitude:(double)pixelY
{
return (M_PI / 2.0 - 2.0 * atan(exp((round(pixelY) - MERCATOR_OFFSET) / MERCATOR_RADIUS))) * 180.0 / M_PI;
}
#pragma mark -
#pragma mark Helper methods
- (MKCoordinateSpan)coordinateSpanWithMapView:(MKMapView *)mapView
centerCoordinate:(CLLocationCoordinate2D)centerCoordinate
andZoomLevel:(double)zoomLevel
{
NSLog(@"in custom zoomlevel-->%f",zoomLevel);
// convert center coordiate to pixel space
double centerPixelX = [self longitudeToPixelSpaceX:centerCoordinate.longitude];
double centerPixelY = [self latitudeToPixelSpaceY:centerCoordinate.latitude];
// determine the scale value from the zoom level
double zoomExponent = 20.0 - zoomLevel;
double zoomScale = pow(2, zoomExponent);
// scale the map’s size in pixel space
CGSize mapSizeInPixels = mapView.bounds.size;
double scaledMapWidth = mapSizeInPixels.width * zoomScale;
double scaledMapHeight = mapSizeInPixels.height * zoomScale;
// figure out the position of the top-left pixel
double topLeftPixelX = centerPixelX - (scaledMapWidth / 2);
double topLeftPixelY = centerPixelY - (scaledMapHeight / 2);
// find delta between left and right longitudes
CLLocationDegrees minLng = [self pixelSpaceXToLongitude:topLeftPixelX];
CLLocationDegrees maxLng = [self pixelSpaceXToLongitude:topLeftPixelX + scaledMapWidth];
CLLocationDegrees longitudeDelta = maxLng - minLng;
// find delta between top and bottom latitudes
CLLocationDegrees minLat = [self pixelSpaceYToLatitude:topLeftPixelY];
CLLocationDegrees maxLat = [self pixelSpaceYToLatitude:topLeftPixelY + scaledMapHeight];
CLLocationDegrees latitudeDelta = -1 * (maxLat - minLat);
// create and return the lat/lng span
MKCoordinateSpan span = MKCoordinateSpanMake(latitudeDelta, longitudeDelta);
return span;
}
#pragma mark -
#pragma mark Public methods
- (void)setCenterCoordinate:(CLLocationCoordinate2D)centerCoordinate
zoomLevel:(double)zoomLevel
animated:(BOOL)animated
{
// clamp large numbers to 28
zoomLevel = MIN(zoomLevel, 28);
// use the zoom level to compute the region
MKCoordinateSpan span = [self coordinateSpanWithMapView:self centerCoordinate:centerCoordinate andZoomLevel:zoomLevel];
MKCoordinateRegion region = MKCoordinateRegionMake(centerCoordinate, span);
// set the region like normal
[self setRegion:region animated:animated];
}
@end
视图控制器中的 #import "MKMapView+ZoomLevel.h"
语句,其中包含MKMapView。
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
double zoomLevel = [self getZoomLevel];
[lblCurrentLevel setText:[NSString stringWithFormat:@"%.2f",zoomLevel]];
NSLog(@"zoomlevel-->%f long-->%f lat-->%f",zoomLevel,mapView.region.span.longitudeDelta,mapView.region.span.latitudeDelta);
}
- (double) getZoomLevel
{
return 21.00 - log2(objMapView.region.span.longitudeDelta * MERCATOR_RADIUS * M_PI / (180.0 * objMapView.bounds.size.width));
}
在上述方法中,您可以根据需要获得缩放级别,您唯一需要做的就是保持初始缩放并将最新的放大/缩小与之比较并再次分配给该变量。
如果有任何疑问,请告知我们我们会解决这个问题:D
修改强>
此源代码来自Troy's Blog。为之前没有提及而道歉。