GMSMapView Draw Custom Polyline in Swift

Question

I made a map view with GMSMapView and I wanted to draw a polyline according to the touch of a finger. but this feature makes me stuck because I have not been able to find the appropriate reference.

in my case example like the result domain app that I want.

Thank you for your help.

Satinet

use the mapView(_ mapView: GMSMapView, didTapAt coordinate: CLLocationCoordinate2D) delegate function to determine where the user tapped and then work out if the tap location is on/near to one of the route paths – Pamella

Hi @ketakiDamale, thank you for your response. but if only using the delegate it can not reach when the finger moves – Satinet

Answer 1

This is a pretty big, complicated question, so I will outline steps for you to follow to implement this. If you need help with a specific step, I suggest you post a separate, specific question.

Here we go:

1. When the "draw mode" button is tapped, add a view above the map

   • Make sure this view takes all touch events so that the map does not scroll when the user draws

   • Subclass this view and override touchesBegan and touchesMoved to actually do the drawing. You can follow the tutorial here for that.

   • Keep an array of all vertices of the polygon in the view's coordinate system.

2. On touchesEnded (when the user stops drawing), convert the points from above to map coordinates.
   • This might help.
3. Draw a polygon from the location coordinates.
   • This will help
4. Remove that view you added in step 1 and turn off drawing mode.

If you need clarification about this process don't hesitate to ask.

Panama

Hi @Dopapp, thank you for your response. You are a genius, after I tried step by step I managed to apply it. it's great to get out of it. once again I am very grateful for your help – Satinet

Answer 2

You should draw the lines using Quartz2D since this question is kind of large i'll just point you to a good reference.

https://www.raywenderlich.com/87899/make-simple-drawing-app-uikit-swift

here you should be able to figure out how to draw to the screen.

Glasses

Hi @cheesey, thank you for your response. using Quartz2D is not possible to apply to GMSMapView because all I need is polyline in the map. because of the polyline form I have to determine which marker is in it or not. – Satinet

@Satinet I see I've never worked with that controller before, so I wasn't exactly sure what the problem was, But I'm glad you found a solution. – Glasses