An example of how a recursive total distance function can be implemented on a list of CLLocation objects.

RecursiveDistance.swift

func totalDistance(initialDistance: CLLocationDistance, initialLocation: CLLocation?, locations: inout [CLLocation]) -> CLLocationDistance {
    if locations.isEmpty {
        return initialDistance
    } else if let initialLocation = initialLocation {
        let firstLocation = locations.removeFirst()
        let distance = firstLocation.distance(from: initialLocation)
        return totalDistance(initialDistance: initialDistance + distance, initialLocation: firstLocation, locations: &locations)
    }
    return totalDistance(initialDistance: initialDistance, initialLocation: locations.removeFirst(), locations: &locations)
}