Lookup for min/max latitude/longitude with one pass on array with the only reduce call

MinMaxCoordinates.swift

// Having array of coordinates you would like show on map you have calculate center and span for map.
// For that you need min/max latitude/longitude of coordinates.

let coordinates = [(CLLocationCoordinate2D(latitude:-40.0, longitude:38.2)),
                   (CLLocationCoordinate2D(latitude:44.2, longitude:17.833)),
                   (CLLocationCoordinate2D(latitude:5.22, longitude:154.2)),
                   (CLLocationCoordinate2D(latitude:33.2, longitude:9.2)),
                   (CLLocationCoordinate2D(latitude:4.2, longitude:3.2))]

// Lookup is done with one pass on array with only reduce
let ((minLatitude, maxLatitude), (minLongitude, maxLongitude)) = coordinates.reduce(((DBL_MAX, DBL_MIN),(DBL_MAX, DBL_MIN))) { r, c in
    (
        (min(c.latitude,r.0.0), max(c.latitude, r.0.1)),
        (min(c.longitude, r.1.0), max(c.longitude, r.1.1))
    )
}

minLatitude // -40
maxLatitude // 44.2
minLongitude // 3.2
maxLongitude // 154.2