title: Passing JSON objects to map coordinates
body: <p>I am populating a NSArray from JSON.</p>
  
  <p>The NSArray is called 'categorias', the latitude and longitude from the object are stored as double in the MySQL database.</p>
  
  <p>Now I am trying to show on a mapView markers from the JSON objects.</p>
  
  <pre><code> for ( int i=0;i&lt;[categorias count];i++){
  
          NSString *lalitudText = [[categorias objectAtIndex:i] objectForKey:@"nombreEmpresa"];
          NSLog(@"QUE ES ESTO--&gt; %@",lalitudText);
  
          GMSMarker *marker = [[GMSMarker alloc] init];
          double latitud = [[categorias objectAtIndex:i] objectForKey:@"latitud"];
          double longitud = [[categorias objectAtIndex:i] objectForKey:@"longitud"];
          marker.position = CLLocationCoordinate2DMake(latitud, longitud);
          marker.title = @"Las Palmas";
          marker.snippet = @"Gran Canaria";
          marker.map = mapView_;
  
      }
  </code></pre>
  
  <p>At following lines I am getting a compiler warning:</p>
  
  <pre><code>double latitud = [[categorias objectAtIndex:i] objectForKey:@"latitud"];
  double longitud = [[categorias objectAtIndex:i] objectForKey:@"longitud"];
  </code></pre>
  
  <p>The warning is: </p>
  
  <pre><code>Initializing 'double' with an expression of incompatible type 'id'
  </code></pre>