Question

I have a map with about 80 annotations. I would like to do 3 things.

1) From my current location, I would like to know the actual route distance to that position. Not the linear distance.

2) I want to be able to show a list of all the annotations, but for every annotation (having lon/lat) I would like to know the actual route distance from my position to that position.

3) I would like to know the closest annotation to my possition using route distance. Not linear distance.

I think the answer to all these three points will be the same. But please keep in mind that I don’t want to create a route, I just want to know the distance to the annotation.

I hope someone can help me.

Best regards,
Paul Peelen

Answer 1

I think as pointed out before, your query would be extremely heavy for google maps API if you perform exactly what you are saying. Do you need all that information at once ? Maybe first it would be good enough to query just some of the distances based on some heuristic or in the user needs.

To obtain the distances, you could use a Google Maps GDirections object… as pointed out here ( at the bottom of the page there’s “Routes and Steps” section, with an advanced example.

“The GDirections object also supports multi-point directions, which can be constructed using the GDirections.loadFromWaypoints() method. This method takes an array of textual input addresses or textual lat/lon points. Each separate waypoint is computed as a separate route and returned in a separate GRoute object, each of which contains a series of GStep objects.“

Using the Google Maps API in the iPhone shouldn’t be too difficult, and I think your question doesn’t cover that, but if you need some basic example, you could look at this question, and scroll to the answer.

Good Luck!