我只是不知道如何计算 MKMapView 上的面积。有谁解决过这个问题吗？
这是我的代码，但它返回太多：
func ringArea() -> Double{
var area: Double = 0
if templocations.count > 2 {
var p1,p2:CLLocationCoordinate2D
for var i = 0; i < templocations.count - 1; i++ {
var loc = templocations[i] as CLLocation
p1 = CLLocationCoordinate2D(latitude: loc.coordinate.latitude, longitude: loc.coordinate.longitude)
loc = templocations[i+1] as CLLocation
p2 = CLLocationCoordinate2D(latitude: loc.coordinate.latitude, longitude: loc.coordinate.longitude)
var sinfunc: Float = (2 + sinf(Float(degreeToRadiant(p1.latitude))) + sinf(Float(degreeToRadiant(p2.latitude))))
area += degreeToRadiant(p2.longitude - p1.longitude) * Double(sinfunc)
}
area = area * kEarthRadius * kEarthRadius / 2;
}
return area
}
斯特凡的回答实施于雨燕5.0 :
import MapKit
let kEarthRadius = 6378137.0
func radians(degrees: Double) -> Double {
return degrees * .pi / 180
}
func regionArea(locations: [CLLocationCoordinate2D]) -> Double {
guard locations.count > 2 else { return 0 }
var area = 0.0
for i in 0..<locations.count {
let p1 = locations[i > 0 ? i - 1 : locations.count - 1]
let p2 = locations[i]
area += radians(degrees: p2.longitude - p1.longitude) * (2 + sin(radians(degrees: p1.latitude)) + sin(radians(degrees: p2.latitude)) )
}
area = -(area * kEarthRadius * kEarthRadius / 2)
return max(area, -area) // In order not to worry about is polygon clockwise or counterclockwise defined.
}
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