如何计算两个坐标距离

TL;DR

let loc1 = CLLocation(latitude: lat1, longitude: lng1)
let loc2 = CLLocation(latitude: lat2, longitude: lng2)
// 计算距离
let meters: CLLocationDistance = loc1.distance(from: loc2)

其实有很多种计算距离的方法啦

• 在线 API：高德、百度
• distance = sqrt( (x1-x2)^2+(y1-y2)2 )
• 球面计算距离？我数学不好
• 本地 API

既然都这么麻烦了，还是用 CoreLocation封装好的distance吧 ，是不是很简洁

/*
*  distanceFromLocation:
*
*  Discussion:
*    Returns the lateral distance between two locations.
*/
@available(iOS 3.2, *)
open func distance(from location: CLLocation) -> CLLocationDistance

那这货是怎么算出来的？看下面官方的描述很靠谱啊

Returns the distance (in meters) from the receiver’s location to the specified location.
This method measures the distance between the two locations by tracing a line between them that follows the curvature of the Earth. The resulting arc is a smooth curve and does not take into account specific altitude changes between the two locations.