Calculates bearing between two points

calculate_bearing.swift

import Foundation
import CoreLocation

/*
θ = atan2( sin Δλ ⋅ cos φ2 , cos φ1 ⋅ sin φ2 − sin φ1 ⋅ cos φ2 ⋅ cos Δλ )
where	φ1,λ1 is the start point, φ2,λ2 the end point (Δλ is the difference in longitude)
*/

func calculateBearing(from: CLLocationCoordinate2D, to: CLLocationCoordinate2D) -> Double {
    let x1 = from.longitude * (Double.pi / 180.0)
    let y1 = from.latitude  * (Double.pi / 180.0)
    let x2 = to.longitude   * (Double.pi / 180.0)
    let y2 = to.latitude    * (Double.pi / 180.0)

    let dx = x2 - x1
    let sita = atan2(sin(dx) * cos(y2), cos(y1) * sin(y2) - sin(y1) * cos(y2) * cos(dx))

    return sita * (180.0 / Double.pi)
}

func coordinate2d(_ latitude: Double, _ longitude: Double) -> CLLocationCoordinate2D {
    return CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
}
       

let osaka = coordinate2d(34.693738, 135.502165)
let tokyo = coordinate2d(35.709026, 139.731992)

let osaka2tokyo = calculateBearing(from: osaka, to: tokyo)
print(osaka2tokyo) // 72.4176293831357  

Can you please check this with

let source = CLLocationCoordinate2D(latitude: -33.8392932, longitude: 151.21519799999999)
 let destination = CLLocationCoordinate2D(latitude: 39.645516999999998, longitude: -104.598724)

This is a source and destination coordinate of MKPolyline, which crosses 180th meridian. The bearing calculated is wrong as I have explained here Do you have suggestions to fix it? :)