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I am trying to create a line on the MKMapView after the users path.

I've found this rather old post, and i'm trying to make it work as explained in the accepted answer:

Does anyone have any examples on how to create a path using MKOverlayPathView?

What is don't get is how to "extract" the array of CLLocation objects mentioned. Right now i have set the mapView setShowsUserLocations:YES, and it updates my movement perfectly fine, so i guess i can get the CLLocations objects somehow, and continuously draw the line?

Im still very now to iOS, so be gentle.

Community
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Anders
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Check out the source code of Apple's BreadCrumb sample app for an example of how to draw the user's path with an MKOverlayView. It does exactly what you are asking and it is quite efficient. It's an excellent example app for getting started with core location and mapkit in iOS.

The idea is to have an object conforming to the MKOverlay protocol that has a property for an array of coordinates that the user has logged. When the user logs a new position you will add a coordinate to this array. Your MKMapViewDelegate is then responsible for providing an MKOverlayView for your overlay. Your MKOverlayView class is then responsible for drawing lines in between the points in the array of the user's logged coordinates. This occurs in the MKOverlayView's drawMapRect:zoomScale:inContext method. Note, you will have to pay special consideration to the fact that drawMapRect:zoomScale:inContext will be called by multiple threads. If you don't acquire a lock on MKOverlay's array of coordinates when adding a new coordinate you will almost definitely experience crashes. See the Breadcrumb code for an efficient way to keep you drawMapRect method thread safe. A less efficient but much simpler alternative is to not access the MKOverlay's array directly from your MKOverlayView but instead pass a copy of it.

Jeff Ames
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The map will show the location pin but it won't actually notify you as your location changes. You want to add your controller as a delegate of CLLocationManager and use startUpdatingLocation. You will then get updates to location that you can save and use to add overlays to the map.

Wain
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  • Thanks! So, when i do as you say, and implement the delegate method "locationManager:didUpdateLocations:" could i use the CLLocations object received, and in this method draw the lines "automatically" when ever the delegate method is sent? And will the CLLocationManager keep updating until i call stopUpdatingLocation:? – Anders Aug 19 '13 at 20:01
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    You could get the existing overlay and add a new point to it I think (don't have the docs to hand just now). – Wain Aug 19 '13 at 20:06