swift4.0 高德地图缩放比例

 ///地图
    lazy var  mapView:MAMapView = {[weak self] in
        let map = MAMapView.init(frame: (self?.view.bounds)!);
        map.delegate = self;
        map.showsUserLocation = true;
        map.userTrackingMode = .followWithHeading;

///设置缩放比例，数值为3-19
        map.zoomLevel = 18;

        return map;
    }()