我一直在尝试计算MKPolygon,我已经在这里进行了一些链接并进行了相应的调整.我似乎无法正确计算平方米.如果需要,我可以提供更多信息
这是我的代码
func polygonArea() -> Double{
var area: Double = 0
var kEarthRadius:Double = 6378137
var coord: NSArray = self.coordinates()
if (coord.count > 2){
var p1, p2, p3 : CLLocationCoordinate2D
var lowerIndex, middleIndex, upperIndex: Int
for var i = 0; i < points.count - 1; i++ {
if (i == (points.count - 2)){
lowerIndex = points.count - 2
middleIndex = points.count - 1
upperIndex = 0
}else if (i == points.count - 1){
lowerIndex = points.count - 1
middleIndex = 0
upperIndex = 1;
}else{
lowerIndex = i
middleIndex = i + 1
upperIndex = i + 2
}
p1 = points[lowerIndex]
p2 = points[middleIndex]
p3 = points[upperIndex]
area += degreesToRadians(p2.longitude - p1.longitude) * (2 + sin(degreesToRadians(p1.latitude)) + sin(degreesToRadians(p2.latitude)))
}
area = area * kEarthRadius * kEarthRadius / 2
}
return area
measureLabel.text = "\(area)"
}
我特别关注了这个链接
MKPolygon area calculation
最佳答案 这是Objective-C版本.您可以在代码中使用它而不会出现任何问题.
#define kEarthRadius 6378137
@implementation MKPolygon (AreaCalculation)
- (double) area {
double area = 0;
NSMutableArray *coords = [[self coordinates] mutableCopy];
[coords addObject:[coords firstObject]];
if (coords.count > 2) {
CLLocationCoordinate2D p1, p2;
for (int i = 0; i < coords.count - 1; i++) {
p1 = [coords[i] MKCoordinateValue];
p2 = [coords[i + 1] MKCoordinateValue];
area += degreesToRadians(p2.longitude - p1.longitude) * (2 + sinf(degreesToRadians(p1.latitude)) + sinf(degreesToRadians(p2.latitude)));
}
area = - (area * kEarthRadius * kEarthRadius / 2);
}
return area;
}
- (NSArray *)coordinates {
NSMutableArray *points = [NSMutableArray arrayWithCapacity:self.pointCount];
for (int i = 0; i < self.pointCount; i++) {
MKMapPoint *point = &self.points[i];
[points addObject:[NSValue valueWithMKCoordinate:MKCoordinateForMapPoint(* point)]];
}
return points.copy;
}
double degreesToRadians(double radius) {
return radius * M_PI / 180;
}
编辑:更新,以便计算也考虑线上的点作为聚合物内部.