cocochina 怎么在view地图

cocochina 怎么在view地图

对原理有兴趣请参见具体的出处 http://troybrant.net/blog/#import#import@interface MKMapView (MapViewUtil)- (void)setCenterCoordinate:(CLLocationCoordinate2D)centerCoordinate zoomLevel:(NSUInteger)zoomLevel animated:(BOOL)animated;@end #import "MapViewUtil.h"#define MERCATOR_OFFSET 268435456#define MERCATOR_RADIUS 85445659.44705395@implementation MKMapView (MapViewUtil)#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:(NSUInteger)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 NSInteger zoomExponent = 20 - 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:(NSUInteger)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