velocity fixes

@@ -337,16 +337,42 @@ import CoreMotion
     }
     
     private func calculateSpeed(lat1: Double, lon1: Double, lat2: Double, lon2: Double, timeDifferenceInSeconds: Double) -> Double {
-        let distance = calculateDistance(lat1: lat1, lon1: lon1, lat2: lat2, lon2: lon2)
+//        let distance = calculateDistance(lat1: lat1, lon1: lon1, lat2: lat2, lon2: lon2)
+        let distance = distanceInKmBetweenEarthCoordinates(lat1: lat1, lon1: lon1, lat2: lat2, lon2: lon2)
 //        print("=== distance: ",distance)
+        
         return (distance / timeDifferenceInSeconds) * 3.6 // Convert to km/h
     }
+    
+    // MARK: distance implementation no1 ===>
+//    private func calculateDistance(lat1: Double, lon1: Double, lat2: Double, lon2: Double) -> Double {
+//        let x = (lon2 - lon1).toRadians() * cos(((lat1 + lat2) / 2).toRadians())
+//        let y = (lat2 - lat1).toRadians()
+//        return sqrt(x * x + y * y) * EARTH_RADIUS
+//    }
+    // <===
+    
+    // MARK: distance implementation no2 ===>
+    func degreesToRadians(degrees: Double) -> Double {
+        return degrees * Double.pi / 180
+    }
+
+    func distanceInKmBetweenEarthCoordinates(lat1: Double, lon1: Double, lat2: Double, lon2: Double) -> Double {
 
-    private func calculateDistance(lat1: Double, lon1: Double, lat2: Double, lon2: Double) -> Double {
-        let x = (lon2 - lon1).toRadians() * cos(((lat1 + lat2) / 2).toRadians())
-        let y = (lat2 - lat1).toRadians()
-        return sqrt(x * x + y * y) * EARTH_RADIUS
+        let earthRadiusKm: Double = 6371
+
+        let dLat = degreesToRadians(degrees: lat2 - lat1)
+        let dLon = degreesToRadians(degrees: lon2 - lon1)
+
+        let lat1 = degreesToRadians(degrees: lat1)
+        let lat2 = degreesToRadians(degrees: lat2)
+
+        let a = sin(dLat/2) * sin(dLat/2) +
+        sin(dLon/2) * sin(dLon/2) * cos(lat1) * cos(lat2)
+        let c = 2 * atan2(sqrt(a), sqrt(1 - a))
+        return earthRadiusKm * c
     }
+    // <===
     
     // Orientation Observer
     func setupOrientationChangeDetection() {
@@ -510,6 +536,26 @@ import CoreMotion
             mLatitude = location.coordinate.latitude
             mLongitude = location.coordinate.longitude
         }
+        
+        // MARK: distance implementation no3 ===>
+        // Get the current location
+//        if let currentLocation = locationManager.location {
+//            // Get the speed in meters per second
+//            let speed = currentLocation.speed
+//            // Convert the speed to kilometers per hour
+//            let speedInKmPerHour = speed * 3.6
+//            
+//            if (speedInKmPerHour >= 0.0) {
+//                mSpeed = speedInKmPerHour
+//            } else {
+//                mSpeed = 0.0
+//            }
+//            
+//            avgVelocityLabel.text = String(format: "%.1f", floor(mSpeed)) + " km/h"
+//            
+////            print("=== speedInKmPerHour: ",String(format: "%.1f", floor(speedInKmPerHour)) + " km/h")
+//        }
+        // <===
     }
 
     public func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {