计算两个CLLocationCoordinate2D位置之间的偏移

import CoreLocation

func calculateDistance(from startLocation: CLLocationCoordinate2D, to endLocation: CLLocationCoordinate2D) -> Double {
    let earthRadius = 6371.0 // 地球半径，单位：公里
    
    let startLatitudeInRadians = startLocation.latitude * Double.pi / 180.0
    let startLongitudeInRadians = startLocation.longitude * Double.pi / 180.0
    let endLatitudeInRadians = endLocation.latitude * Double.pi / 180.0
    let endLongitudeInRadians = endLocation.longitude * Double.pi / 180.0
    
    let latitudeDifference = endLatitudeInRadians - startLatitudeInRadians
    let longitudeDifference = endLongitudeInRadians - startLongitudeInRadians
    
    let a = sin(latitudeDifference/2) * sin(latitudeDifference/2) +
            cos(startLatitudeInRadians) * cos(endLatitudeInRadians) *
            sin(longitudeDifference/2) * sin(longitudeDifference/2)
    let c = 2 * atan2(sqrt(a), sqrt(1-a))
    
    let distance = earthRadius * c // 距离，单位：公里
    return distance
}

// 示例用法
let startLocation = CLLocationCoordinate2D(latitude: 39.9087, longitude: 116.3975)
let endLocation = CLLocationCoordinate2D(latitude: 31.2244, longitude: 121.4758)

let distance = calculateDistance(from: startLocation, to: endLocation)
print("两个位置之间的距离为：\(distance)公里")