Ios Google map SDK cannot create dashed polylines

Question

I named the method below for drawing dotted polylines between markers. When it comes to execution, it shows that only solid lines are drawn. Could you tell me how to draw dashed lines on a Google map?

- (void) createDashedLine:(CLLocationCoordinate2D )thisPoint:(CLLocationCoordinate2D )nextPoint: (UIColor *)colour { NSLog(@"next pt latitude %ff" , nextPoint.latitude); NSLog(@"next pt longitude %ff" , nextPoint.longitude); NSLog(@"this pt laatitude %ff" , thisPoint.latitude); NSLog(@"this pt longitude %ff" , thisPoint.longitude); double difLat = nextPoint.latitude - thisPoint.latitude; double difLng = nextPoint.longitude - thisPoint.longitude; double scale = camera.zoom * 2; double divLat = difLat / scale; double divLng = difLng / scale; CLLocationCoordinate2D tmpOrig= thisPoint; GMSMutablePath *singleLinePath = [GMSMutablePath path]; for(int i = 0 ; i < scale ; i ++){ CLLocationCoordinate2D tmpOri = tmpOrig; if(i > 0){ tmpOri = CLLocationCoordinate2DMake(tmpOrig.latitude + (divLat * 0.25f), tmpOrig.longitude + (divLng * 0.25f)); } [singleLinePath addCoordinate:tmpOri]; [singleLinePath addCoordinate: CLLocationCoordinate2DMake(tmpOrig.latitude + (divLat * 1.0f), tmpOrig.longitude + (divLng * 1.0f))]; tmpOri = CLLocationCoordinate2DMake(tmpOrig.latitude + (divLat * 1.0f), tmpOrig.longitude + (divLng * 1.0f)); } GMSPolyline *polyline ; polyline = [GMSPolyline polylineWithPath:singleLinePath]; polyline.geodesic = NO; polyline.strokeWidth = 5.f; polyline.strokeColor = colour; polyline.map = mapView_; //Setup line style and draw _lengths = @[@([singleLinePath lengthOfKind:kGMSLengthGeodesic] / 50)]; _polys = @[polyline]; [self setupStyleWithColour:colour]; [self tick]; } - (void)tick { //Create steps for polyline(dotted polylines) for (GMSPolyline *poly in _polys) { poly.spans = GMSStyleSpans(poly.path, _styles, _lengths, kGMSLengthGeodesic, _pos); } _pos -= _step; } -(void)setupStyleWithColour:(UIColor *)color{ GMSStrokeStyle *gradColor = [GMSStrokeStyle gradientFromColor:color toColor:color]; _styles = @[gradColor,[GMSStrokeStyle solidColor:[UIColor colorWithWhite:0 alpha:0]],]; _step = 50000; } - (void)addMarkers { // NSMutableArray *polys = [NSMutableArray array]; if([CarArray count] > 0){ GMSMutablePath *path = [GMSMutablePath path]; GMSMutablePath *currentPath = [GMSMutablePath path]; GMSPolyline *polyline ; GMSPolyline *polylineC ; GMSMarker *marker; for (int i = 0; i < [CarArray count]; i++) { CheckPoints *cp = [CarArray objectAtIndex:i]; CLLocationCoordinate2D position = CLLocationCoordinate2DMake(cp.getLatitude , cp.getLongitude); marker = [GMSMarker markerWithPosition:position]; // GMSMarker *marker = [[GMSMarker alloc] init]; marker.position = position; NSLog( @"%d", cp.getState ); NSLog( @"%f", cp.getLatitude); NSLog( @"%f", cp.getLongitude ); NSLog( @"%@", cp.getDesp ); marker.title = cp.getDesp; marker.zIndex = 1; NSString *tmpLat = [[NSString alloc] initWithFormat:@"%f", position.latitude]; NSString *tmpLong = [[NSString alloc] initWithFormat:@"%f", position.longitude]; marker.snippet = [NSString stringWithFormat:@"%@ %@", tmpLat,tmpLong]; UIColor *color; if (cp.getState ==0) { color = [UIColor greenColor]; } else { color = [UIColor redColor]; } if([CarArray count] > 2){ [path addLatitude:cp.getLatitude longitude:cp.getLongitude]; if(i > [CarArray indexOfObject:CarArray.lastObject] -2){ [currentPath addLatitude:cp.getLatitude longitude:cp.getLongitude]; } }else{ [currentPath addLatitude:cp.getLatitude longitude:cp.getLongitude]; } marker.icon = [GMSMarker markerImageWithColor:color]; marker.map = mapView_; // mapView_.selectedMarker = marker; } if([CarArray count] > 2) { polyline = [GMSPolyline polylineWithPath:currentPath]; polyline.geodesic = YES; polyline.strokeWidth = 5.f; polyline.strokeColor = [UIColor greenColor]; polyline.map = mapView_; _lengths = @[@([currentPath lengthOfKind:kGMSLengthGeodesic] / 50)]; _polys = @[polyline]; [self setupStyleWithColour:[UIColor greenColor]]; [self tick]; for(int i = 0 ; i < [currentPath count] -1 ; i++){ CLLocationCoordinate2D thisPoint = [currentPath coordinateAtIndex:i]; CLLocationCoordinate2D nextPoint = [currentPath coordinateAtIndex:i+1]; NSLog(@"next pt s latitude %ff" , nextPoint.latitude); NSLog(@"next pt s longitude %ff" , nextPoint.longitude); NSLog(@"this pt s latitude %ff" , thisPoint.latitude); NSLog(@"this pt s longitude %ff" , thisPoint.longitude); [self drawArrowLines:mapView_ :thisPoint :nextPoint :[UIColor greenColor]:i+1: false]; [self createDashedLine: thisPoint :nextPoint :[UIColor greenColor]]; } GMSMutablePath *path2 = [GMSMutablePath path]; GMSMutablePath *path3 = [GMSMutablePath path]; path2 = path.mutableCopy; [path2 removeLastCoordinate]; path3 = path2; polylineC = [GMSPolyline polylineWithPath:path3]; polylineC.geodesic = YES; polylineC.strokeWidth = 5.f; polylineC.map = mapView_; _lengths = @[@([currentPath lengthOfKind:kGMSLengthGeodesic] / 50)]; _polys = @[polylineC]; [self setupStyleWithColour:[UIColor greenColor]]; [self tick]; // polylineC.strokeColor = [UIColor redColor]; for(int i = 0 ; i < [path count] -1 ; i++){ CLLocationCoordinate2D thisPoint = [path coordinateAtIndex:i]; CLLocationCoordinate2D nextPoint = [path coordinateAtIndex:i+1]; NSLog(@"next pt s latitude %ff" , nextPoint.latitude); NSLog(@"next pt s longitude %ff" , nextPoint.longitude); NSLog(@"this pt s latitude %ff" , thisPoint.latitude); NSLog(@"this pt s longitude %ff" , thisPoint.longitude); [self drawArrowLines:mapView_ :thisPoint :nextPoint :[UIColor redColor]: i+1 : true]; [self createDashedLine: thisPoint :nextPoint :[UIColor redColor]]; } }else{ polyline = [GMSPolyline polylineWithPath:currentPath]; polyline.geodesic = NO; polyline.strokeWidth = 5.f; polyline.strokeColor = [UIColor greenColor]; polyline.map = mapView_; _lengths = @[@([currentPath lengthOfKind:kGMSLengthGeodesic] / 50)]; _polys = @[polyline]; [self setupStyleWithColour:[UIColor greenColor]]; [self tick]; for(int i = 0 ; i < [currentPath count] -1 ; i++){ CLLocationCoordinate2D thisPoint = [currentPath coordinateAtIndex:i]; CLLocationCoordinate2D nextPoint = [currentPath coordinateAtIndex:i+1]; NSLog(@"next pt s latitude %ff" , nextPoint.latitude); NSLog(@"next pt s longitude %ff" , nextPoint.longitude); NSLog(@"this pt s latitude %ff" , thisPoint.latitude); NSLog(@"this pt s longitude %ff" , thisPoint.longitude); [self drawArrowLines:mapView_ :thisPoint :nextPoint :[UIColor greenColor] : i+1 : false]; [self createDashedLine: thisPoint :nextPoint :[UIColor greenColor]]; } } } } 

Answer 1

Yes, for a dashed line, you need to configure a few things.

Define a few variables first

 NSArray *_styles; NSArray *_lengths; NSArray *_polys; double _pos, _step; 

Define in function outside for..loop not inside how you do

 - (void) createDashedLine:(CLLocationCoordinate2D )thisPoint:(CLLocationCoordinate2D )nextPoint: (UIColor *)colour { double difLat = nextPoint.latitude - thisPoint.latitude; double difLng = nextPoint.longitude - thisPoint.longitude; double scale = camera.zoom * 2; double divLat = difLat / scale; double divLng = difLng / scale; CLLocationCoordinate2D tmpOrig= thisPoint; GMSMutablePath *singleLinePath = [GMSMutablePath path]; for(int i = 0 ; i < scale ; i ++){ CLLocationCoordinate2D tmpOri = tmpOrig; if(i > 0){ tmpOri = CLLocationCoordinate2DMake(tmpOrig.latitude + (divLat * 0.25f), tmpOrig.longitude + (divLng * 0.25f)); } [singleLinePath addCoordinate:tmpOri]; [singleLinePath addCoordinate: CLLocationCoordinate2DMake(tmpOrig.latitude + (divLat * 1.0f), tmpOrig.longitude + (divLng * 1.0f))]; tmpOri = CLLocationCoordinate2DMake(tmpOrig.latitude + (divLat * 1.0f), tmpOrig.longitude + (divLng * 1.0f)); } GMSPolyline *polyline ; polyline = [GMSPolyline polylineWithPath:singleLinePath]; polyline.geodesic = NO; polyline.strokeWidth = 5.f; polyline.strokeColor = colour; polyline.map = mapView_; //Setup line style and draw _lengths = @[@([singleLinePath lengthOfKind:kGMSLengthGeodesic] / 100)]; _polys = @[polyline]; [self setupStyleWithColour:colour]; [self tick]; } - (void)tick { //Create steps for polyline(dotted polylines) for (GMSPolyline *poly in _polys) { poly.spans = GMSStyleSpans(poly.path, _styles, _lengths, kGMSLengthGeodesic, _pos); } _pos -= _step; } -(void)setupStyleWithColour:(UIColor *)color{ GMSStrokeStyle *gradColor = [GMSStrokeStyle gradientFromColor:color toColor:color]; _styles = @[ gradColor, [GMSStrokeStyle solidColor:[UIColor colorWithWhite:0 alpha:0]], ]; _step = 50000; } 

Hope this helps. Greetings.

Answer 2

Creating a dashed line on Google maps is as simple as that. This defines a polyline with a green and transparent alternating pattern.

 GMSMutablePath *path = [GMSMutablePath path]; for (...) { // add coordinate to your path [path addCoordinate:CLLocationCoordinate2DMake(latitude, longitude)]; } GMSPolyline *polyline = [GMSPolyline polylineWithPath:path]; polyline.map = self.mapView; polyline.strokeWidth = 3.0; NSArray *styles = @[[GMSStrokeStyle solidColor:[UIColor greenColor]], [GMSStrokeStyle solidColor:[UIColor clearColor]]]; NSArray *lengths = @[@25, @20]; polyline.spans = GMSStyleSpans(polyline.path, styles, lengths, kGMSLengthRhumb); 

If you need a dashed line, you can adjust the length to

 NSArray *lengths = @[@10, @10]; 

Answer 3

Everyone who needs the length of the line segments does not depend on the level of map scaling, here my solution is quick. I create a polyline in the same way as in this answer , then right after that and in func mapView(mapView: GMSMapView, didChangeCameraPosition position: GMSCameraPosition) I call this method:

 func updateLine() { let styles = [ GMSStrokeStyle.solidColor(UIColor.blackColor()), GMSStrokeStyle.solidColor(UIColor.clearColor()) ] let scale = 1.0 / mapView.projection.pointsForMeters(1, atCoordinate: mapView.camera.target) line.spans = GMSStyleSpans(line.path!, styles, [15.0 * scale, 10.0 * scale], kGMSLengthRhumb) } 

15.0 and 10.0 - segment lengths in points.

Answer 4

Here is the translation of Swift 3.0

 //Returns a GMSPath parsed from gpx file path = GpxProcessor(fileNames: "test.gpx").getPolygons() redPolyline = GMSPolyline(path: path) redPolyline.geodesic = true redPolyline.map = mapView let styles = [GMSStrokeStyle.solidColor(.clear), GMSStrokeStyle.solidColor(.red)] let lengths: [NSNumber] = [10, 10] redPolyline.spans = GMSStyleSpans(redPolyline.path!, styles, lengths,GMSLengthKind.rhumb)