我通过创建一个NSObject子类并符合MKOverlay协议以及一个MKOverlayPathRenderer的子类来制作了自定义覆盖层。我的目标是创建一个圆形覆盖层,将其锚定到MKMapView上的用户位置,并且我已经成功实现了这一点。每当我的覆盖层的坐标被设置时,使用键值观察的渲染器会使其绘制的路径无效化,然后重新绘制。
但是我遇到的问题是,我希望圆的半径是以米为单位的,但我认为我的数学计算有误或者我漏掉了什么东西。我在下面发布了覆盖对象和渲染器的源代码(渲染器的接口中没有任何内容)。例如,我将半径设置为200米,但在地图视图上,它只显示大约10米。有人知道如何解决这个问题吗?
但是我遇到的问题是,我希望圆的半径是以米为单位的,但我认为我的数学计算有误或者我漏掉了什么东西。我在下面发布了覆盖对象和渲染器的源代码(渲染器的接口中没有任何内容)。例如,我将半径设置为200米,但在地图视图上,它只显示大约10米。有人知道如何解决这个问题吗?
//Custom Overlay Object Interface
@import Foundation;
@import MapKit;
@interface CustomRadiusOverlay : NSObject <MKOverlay>
+ (id)overlayWithCoordinate:(CLLocationCoordinate2D)coordinate radius:(CLLocationDistance)radius;
@property (nonatomic) CLLocationCoordinate2D coordinate;
@property (nonatomic) MKMapRect boundingMapRect;
@property (nonatomic) CLLocationDistance radius;
@end
//Custom overlay
#import "CustomRadiusOverlay.h"
@implementation LFTRadiusOverlay
+ (id)overlayWithCoordinate:(CLLocationCoordinate2D)coordinate radius:(CLLocationDistance)radius{
CustomRadiusOverlay* overlay = [LFTRadiusOverlay new];
overlay.coordinate = coordinate;
overlay.radius = radius;
return overlay;
}
- (MKMapRect)boundingMapRect{
MKMapPoint upperLeft = MKMapPointForCoordinate(self.coordinate);
MKMapRect bounds = MKMapRectMake(upperLeft.x, upperLeft.y, self.radius*2, self.radius*2);
return bounds;
}
- (void)setCoordinate:(CLLocationCoordinate2D)coordinate{
_coordinate = coordinate;
self.boundingMapRect = self.boundingMapRect;
}
@end
#import "CustomOverlayRadiusRenderer.h"
#import "CustomRadiusOverlay.h"
@interface CustomOverlayRadiusRenderer()
@property (nonatomic) CustomRadiusOverlay* circleOverlay;
@end
@implementation CustomOverlayRadiusRenderer
- (id)initWithOverlay:(id<MKOverlay>)overlay{
self = [super initWithOverlay:overlay];
if(self){
_circleOverlay = (LFTRadiusOverlay*)overlay;
[_circleOverlay addObserver:self forKeyPath:@"coordinate" options:NSKeyValueObservingOptionNew context:NULL];
self.fillColor = [UIColor redColor];
self.alpha = .7f;
}
return self;
}
- (void)createPath{
CGMutablePathRef path = CGPathCreateMutable();
MKMapPoint mapPoint = MKMapPointForCoordinate(self.circleOverlay.coordinate);
CGPoint point = [self pointForMapPoint:mapPoint];
CGPathAddArc(path, NULL, point.x, point.y, self.circleOverlay.radius, 0, kDegreesToRadians(360), YES);
self.path = path;
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
[self invalidatePath];
}
@end