I am developing iOS application including GoogleMaps.
And implementation process of GoogleMaps SDK for iOS was completed yet.
But I want to know how to calculate GMSCamera zoom
for showing whole route on Map.
In Apple Map, we use span, maybe.
But GoogleMaps SDK doesn't have span.
Please give me advice.
Actually in the current version of the SDK you can use fitBounds:
GMSCoordinateBounds *bounds = [[GMSCoordinateBounds alloc] initWithPath:yourPath];
//There are several useful init methods for the GMSCoordinateBounds!
GMSCameraUpdate *update = [GMSCameraUpdate fitBounds:bounds];
[mapView_ moveCamera:update];
This way you let the math to Google, and I'm pretty sure they are really good at it.
Here is a function that may help as this calculates the zoomLevel from an MKMapView that is "Google Compatible"
- (NSInteger)getZoomLevel
{
MKMapView *map = (MKMapView *)self.mapView;
CLLocationDegrees longitudeDelta = map.region.span.longitudeDelta;
CGFloat mapWidthInPixels = map.bounds.size.width;
double zoomScale = longitudeDelta * 85445659.44705395 * M_PI / (180.0 * mapWidthInPixels);
double zoomer = 20 - log2(zoomScale);
if ( zoomer < 0 ) zoomer = 0;
return (NSInteger)zoomer;
}
If you can grab the coordinates and pass those in instead you should be ok.
Lee's method is right, but the math is not right, based on google maps ios sdk document on zoom
Increasing the zoom level by 1 doubles the width of the world on the
screen. Hence at zoom level N, the width of the world is approximately
256 * 2^N, i.e., at zoom level 2, the whole world is approximately 1024
points wide. Note that the zoom level need not be an integer. The
range of zoom levels permitted by the map depends on a number of
factors including location, map type and screen size.
The math to calculate the zoom should be
zoom = log2(360 * mapView.bounds.size.width/ longitudeDelta) - 8;
I posted an answer to a similar question here:
How to setRegion with google maps sdk for iOS?
It uses a similar approach to Lee's answer: Convert the lat/lon to pixels, calculate a scale, then a zoom level.
Swift:
//Create a path
let path = GMSMutablePath()
//for each point you need, add it to your path
let position = CLLocationCoordinate2DMake(latitude, longitude)
path.add(position)
//Update your mapView with path
let mapBounds = GMSCoordinateBounds(path: path)
let cameraUpdate = GMSCameraUpdate.fit(mapBounds)
mapView.moveCamera(cameraUpdate)
Jing, your math is correct for longitudes, but for latitudes it has to be a bit more tricky. Mercator projection handles latitudes and longitudes differently. I have posted the correct code here: https://stackoverflow.com/a/16217785/2291425
Use GMSCoordinateBounds. You can fit the map using different parameters like cooodinates, bounds etc.
GMSCoordinateBounds *bounds = [[GMSCoordinateBounds alloc] initWithPath:path];
https://developers.google.com/maps/documentation/ios/reference/interface_g_m_s_coordinate_bounds#a583bf55d8dd8cd10eec3473688f9d788
Related
I need to draw lines to demonstrate transportation of goods on apple maps. To clarify start- and end-point, I draw a little arrowhead on the destination side.The arrowhead is drawn separately but it is reversed in one case.
>-->-->-->-
instead of
<--<--<--<-
I am using MKMapView and MKPolyline to draw lines. I am using MKOverlay to add direction arrows. The steps I follow are,
calculate bearing of
Source : CLLocationCoordinate2D(latitude: -33.8392932, longitude: 151.21519799999999)
Destination: CLLocationCoordinate2D(latitude: 39.645516999999998, longitude: -104.598724)
using the following function
open static func getDirectionOf( _ supplyLineWithCoordinates: [CLLocationCoordinate2D]) -> CGFloat {
guard let sourceCoordniate = supplyLineWithCoordinates.first,
let destinationCoordniate = supplyLineWithCoordinates.last else {
fatalError("Coordinates of supply line not found")
}
let sourcePoint: MKMapPoint = MKMapPointForCoordinate(sourceCoordniate)
let destinationPoint: MKMapPoint = MKMapPointForCoordinate(destinationCoordniate)
let x: Double = destinationPoint.x - sourcePoint.x
let y: Double = destinationPoint.y - sourcePoint.y
var arrowDirection = CGFloat(fmod(atan2(y, x), 360.0))
if arrowDirection < 0.0 {
arrowDirection += 2 * .pi
}
return arrowDirection
}
Rotate the arrow image and add it as the map overlay. The directions are calculated correctly in most of the cases, however, when I select the line shown below the direction is displayed 180 opposite. It starts from Sydney, Australia and ends in Denver, US
When trying to display the region with this two locations in mapView.setVisibleMapRect these region is not displayed, mapview tries to display region starting from Sydney (Australia) to Denver(US) through Asia and Europe, while it should display the map area I have attached above. If you have suggestions for optimisation, feel free to mention it.
I think this might be the reason, the direction should be calculated along the red line but it being calculated along the green line. Both lines are drawn by connecting same location coordinates in map. Any known workaround for this?
I solved it in a dirty way by converting coordinate to CGPoint and then calculating bearing between Points.
let destinationPoint = mapView.convert(destination, toPointTo: nil)
let sourcePoint = mapView.convert(source, toPointTo: nil)
let bearing = atan2(sourcePoint.y - destinationPoint.y, sourcePoint.x - destinationPoint.x) - .pi
Caution: This calculation will go wrong when map is rotated
I´m developing an iPhone app, and I need some help with this case:
I need to check, if user leave google maps route (GMSPolyline) and if distance from user location to nearest point of route is more than 40 meters -- I need to rebuild route.
I can't find the right algorithm to detect if distance from user to route is more than 40 meters.
I've tried to use this method to find projection of user location (converted to CGPoint by CGPointMake) on route :
+ (CGPoint)projectionOfPoint:(CGPoint)origPoint toSegmentP1:(CGPoint)p1 p2:(CGPoint)p2 {
// for case line is parallel to x axis
if (p2.y == p1.y) {
return CGPointMake(origPoint.x, p1.y);
// for case line is parallel to y axis
} else if (p2.x == p1.x) {
return CGPointMake(p1.x, origPoint.y);
}
// line from segment
CGFloat kKoefLine1 = (p2.x - p1.x)/(p2.y - p1.y);
CGFloat bKoefLine1 = p1.y - kKoefLine1*p1.x;
// perpendicular line
CGFloat kKoefLine2 = -1/kKoefLine1;
CGFloat bKoefLine2 = origPoint.y - kKoefLine2*origPoint.x;
// cross point
CGFloat krossX = (bKoefLine2 - bKoefLine1)/(kKoefLine1 - kKoefLine2);
CGFloat krossY = kKoefLine2*krossX + bKoefLine2;
return CGPointMake(krossX, krossY);}
Then I calculate distance from returned projection (converted to CLLocation) and user location, but it doesn't works.
P.S.: I will be thankful if solution would be written on swift.
There is a GMSGeometryIsLocationOnPath function in the GMSGeometryUtils module in the Google Maps SDK.
You should be able to use that to calculate what you need.
Pseudocode (not tested):
let currentLocation: CLLocationCoordinate2D = ...
let routePath: GMSPath = routePolyline.path
let geodesic = true
let tolerance: CLLocationDistance = 40
let within40Meters = GMSGeometryIsLocationOnPath(currentLocation, routePath, geodesic, tolerance)
for swift 5.0 and based on #Arthur answer I wrote follwoing function
func isInRoute(posLL: CLLocationCoordinate2D, path: GMSPath) -> Bool
{
let geodesic = true
let tolerance: CLLocationDistance = 40
let within40Meters = GMSGeometryIsLocationOnPathTolerance(posLL, path, geodesic, tolerance)
return within40Meters
}
While I don't recall much about the GMS SDK off the top of my head, before I give you an answer, I will say that nobody on here will write your code for you. That's your job and should be done on your time. You haven't given any background as to how far you've gotten in terms of calculating routes, whether or not you've figured out how to calculate distance at all, etc.
With that being said, routes on Google Maps are comprised of "legs", which denote a path to take before a turn is made in efforts to reach the end destination. By querying your "route" dictionary, you can extract an array of dictionaries where each element (which is a dictionary) contains metadata about a "leg". You can then loop through that array, go through each dictionary and extract the "distance" value, and sum them to a single "distance" var.
You can recalculate this as often as needed and use a conditional to check whether or not the leg distance sum is < 40M, else rebuild.
link to an article that should help (I didn't have the time to go through the entire thing for you, so do your due diligence and research) here.
I am working on an iOS application that works like Uber. When the device moves I am moving the car marker as well. But am not able to turn it as per turns on road like Uber does. How can I make it possible?
Also how can I keep this car marker only on road?
You can calculate bearing then rotate marker based on the calculated bearing.
Use this function to calculate bearing:
+(float)getBearing:(CLLocationCoordinate2D)locations1 andSecond:(CLLocationCoordinate2D)locattion2
{
float fLat = degreesToRadians(locations1.latitude);
float fLng = degreesToRadians(locations1.longitude);
float tLat = degreesToRadians(locattion2.latitude);
float tLng = degreesToRadians(locattion2.longitude);
float degree = radiansToDegrees(atan2(sin(tLng-fLng)*cos(tLat), cos(fLat)*sin(tLat)-sin(fLat)*cos(tLat)*cos(tLng-fLng)));
if (degree >= 0) {
return degree;
} else {
return 360+degree;
}
}
Then rotate the marker itself using rotation property
marker.rotation = CALCULATED_BEARING - 180;
Take a look at rotating the marker alongside the update or the moving of locations with regards to the bearing. Not really sure how you can achieve with keeping the marker on the road since you are relying on the gps to provide exact location where you will place your marker.
Take a look at this SO as a sample.
I'm querying my server for a list of locations that are closest to the user based on his observable portion of the mapview.
I'm not entirely sure on how to do this, but should I send the center lat and long of the mapview's visible region and then search for results based on nearest radius?
I know that MKMapView has two properties called region and visibleMapRect. Should I use one of those, and if so, which one is more appropriate based on my question?
EDIT
I'm looking to implement functionality that's identical to the apple maps and Yelp app when you search for nearby locations and it shows you what's relevant based off the visible portion of the map view.
EDIT 2
I have seen a lot of people break up the visible portion of their mapview into quadrants, most commonly NW,NE,SW and SE. However, I'm still not entirely sure why theyr'e doing this. I would like to know the best way to query the back end, which contains a lat and long for each location, to find the locations which exist on the mapview.
I have looked everywhere on stackoverflow and I found a similar question here. However, it doesn't answer my question and there's no mention of visibleMapRect because it's over 5 years old.
Any help is tremendously appreciated.
So you would need to provide your server call with these 2 coord bottomleft and topright 4 points all together.
if lat of location > bottomleft.lat and if lat of location < topright.lat
if long of location > bottomleft.long and if long of location < topright.long
iOS Code would look like this the make server call with these four variables as parameters
fun viewDidLoad() {
super.viewDidLoad()
self.mapView.delegate = self
}
func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
// Using region
var span: MKCoordinateSpan = mapView.region.span
var center: CLLocationCoordinate2D = mapView.region.center
// This is the farthest Lat point to the left
var farthestLeft = center.latitude - span.latitudeDelta * 0.5
// This is the farthest Lat point to the Right
var farthestRight = center.latitude + span.latitudeDelta * 0.5
// This is the farthest Long point in the Upward direction
var farthestTop = center.longitude - span.longitudeDelta * 0.5
// This is the farthest Long point in the Downward direction
var farthestBottom = center.longitude + span.longitudeDelta * 0.5
var SWCoord = MKCoordinateForMapPoint(farthestBottom, farthestLeft)
var NECoord = MKCoordinateForMapPoint(farthestTop, farthestRight)
// Using visibleMapRect
var mapRect = mapView.visibleMapRect
// This is the top right Coordinate
var NECoord = getCoordinateFromMapRectanglePoint(MKMapRectGetMaxX(mapRect), y: mapRect.origin.y)
// This is the bottom left Coordinate
var SWCoord = getCoordinateFromMapRectanglePoint(mapRect.origin.x, y: MKMapRectGetMaxY(mapRect))
// Not needed but could be useful
// var NWCoord = getCoordinateFromMapRectanglePoint(MKMapRectGetMinX(mapRect), y: mapRect.origin.y)
// var SECoord = getCoordinateFromMapRectanglePoint(MKMapRectGetMaxX(mapRect), y: MKMapRectGetMaxY(mapRect))
}
func getCoordinateFromMapRectanglePoint(x: Double, y: Double) -> CLLocationCoordinate2D {
var mapPoint = MKMapPointMake(x, y)
return MKCoordinateForMapPoint(mapPoint)
}
If you have anymore questions just comment
EDIT 2 I have seen a lot of people break up the visible portion of their mapview into quadrants, most commonly NW,NE,SW and SE.
However, I'm still not entirely sure why theyr'e doing this. I would
like to know the best way to query the back end, which contains a lat
and long for each location, to find the locations which exist on the
mapview.
I'm not sure if this is what you're referring to but they could be using quadtrees as a way to efficiently search the locations of a huge amount of coordinates.
This post from Thoughtbot demonstrates how to use quadtrees to display thousands of place coordinates as clusters on the map and it includes gifs that very succinctly explain how it works:
A quad tree is a data structure comprising nodes which store a bucket of points and a bounding box. Any point which is contained within the node’s bounding box is added to its bucket. Once the bucket gets filled up, the node splits itself into four nodes, each with a bounding box corresponding to a quadrant of its parents bounding box. All points which would have gone into the parent’s bucket now go into one of its children’s buckets.
Source: How To Efficiently Display Large Amounts of Data on iOS Maps
Basically i have a list of POI's (name,lat,long) and i want to draw them on the UIView, relative to my current lat/long. I'm looking for some best practice for mapping these POI (lat/long) to a UIView.
I don't want to use MKMapView (no need for displaying map-data).
I was reading:
http://developer.apple.com/library/ios/#documentation/general/conceptual/Devpedia-CocoaApp/CoordinateSystem.html
But I'm clueless how i get from a CLLocation to a (x,y) on my UIView. I only want to draw those POI's around my current location. So, for example if my screen would represent a 20 by 30 KM region, how do i map my POI's to their corresponding (x,y) coordinates?
Thanks.
What you're doing is a little strange, but you can convert latitude/longitude to a CGPoint-like struct called an MKMapPoint. An MKMapPoint has an x and y value which correspond to points on a map. Imagine if you laid out a flat map of the world, and 0,0 was the top left. MKMapPoint is a point on that map using that coordinate system.
Use the function MKMapPointForCoordinate() to convert a CLLocationCoordinate2D to an MKMapPoint
MKMapPoint myMapPoint = MKMapPointForCoordinate(myLocationCoordinate);
When you get the list of points, you'll have to do something like finding the max and min x and y values, then fitting all the points into your view using those values, otherwise you'll end up with a load of very close points in one place in your view.
My guess is that, for a 20KM by 30KM region, you can consider the earth to be flat and there fore linearly extrapolate the coordinates. I am sure you can google and find out as to how much distance is a difference in 0.00001 in latitude and longitude.
So if you have 20Km to be represented on X axis, and your current location is 30.1234567 in latitude, and 0.0000001 is 1 km then you can put your coordinate in the center of the screen and 30.1234557 as the left most X coordinate and so on.
I am not trying to provide an answer here, but just trying to think out loud, because I wanted to do some thing similar as well and did it as an Internet based app (without display though), where given two coordinates, I had to find the distance between them.
There are many (many) different approaches to modelling the planet and translating 3D coordinates onto a 2D surface, and the errors introduced by the various methods vary depending on what part of the globe you are. This question seems to cover most of what you are after though:
Converting Longitude & Latitude to X Y on a map with Calibration points
I think its best way (correctly work for Mercator projection map):
extension UIView
{
func addLocation(coordinate: CLLocationCoordinate2D)
{
// max MKMapPoint values
let maxY = Double(267995781)
let maxX = Double(268435456)
let mapPoint = MKMapPointForCoordinate(coordinate)
let normalizatePointX = CGFloat(mapPoint.x / maxX)
let normalizatePointY = CGFloat(mapPoint.y / maxY)
let pointView = UIView(frame: CGRectMake(0, 0, 5, 5))
pointView.center = CGPointMake(normalizatePointX * frame.width, normalizatePointY * frame.height)
pointView.backgroundColor = UIColor.blueColor()
addSubview(pointView)
}
}
My simple project for adding coordinate on UIView: https://github.com/Glechik/MapCoordinateDrawer