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copied!<p>You would generally have a property in you <code>UIView</code> subclass for your coordinate (either using your <code>CGPoint</code> or perhaps a <code>CLLocationCoordinate2D</code>) and then call <code>setNeedsDisplay</code> so that the device knows that it needs to call your <code>drawRect</code> method.</p> <p>Thus, have a property:</p> <pre><code>@property (nonatomic) CLLocationCoordinate2D coordinate; </code></pre> <p>And then update the implementation of your view as such:</p> <pre><code>- (void)setCoordinate:(CLLocationCoordinate2D)coordinate { _coordinate = coordinate; [self setNeedsDisplay]; } - (void)drawRect:(CGRect)rect { CGPoint newCoord = [self convertLatLongCoord:self.coordinate]; NSLog(@"Cartesian Coordinate: (%f, %f)",newCoord.x, newCoord.y); //Draw dot at coordinate CGColorRef darkColor = [[UIColor colorWithRed:21.0/255.0 green:92.0/255.0 blue:136.0/255.0 alpha:1.0] CGColor]; CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetFillColorWithColor(context, darkColor); CGContextSetStrokeColorWithColor(context, darkColor); CGContextFillRect(context, CGRectMake(newCoord.x, newCoord.y, 100.0, 100.0)); } // I assume you're using the algorithm from here: https://stackoverflow.com/a/1185413/1271826 - (CGPoint)convertLatLongCoord:(CLLocationCoordinate2D)coordinate { CGFloat x = EARTH_RADIUS * cos(coordinate.latitude * M_PI / 180.0) * cos(coordinate.longitude * M_PI / 180.0); CGFloat y = EARTH_RADIUS * cos(coordinate.latitude * M_PI / 180.0) * sin(coordinate.longitude * M_PI / 180.0); // TODO: The above calculates x and y values from -EARTH_RADIUS to EARTH_RADIUS. // You presumably want to scale this appropriately for your view. The // specifics will vary based upon your desired user interface. return CGPointMake(x, y); } </code></pre> <p>Then, when you want to update your view, you can do something like:</p> <pre><code>myCustomView.coordinate = CLLocationCoordinate2DMake(41.998035, -116.012215); </code></pre> <p>While I've tried to remedy some flaws in <code>convertLatLongCoord</code>, it's still not perfect, as it will yield values ranging from <code>-EARTH_RADIUS</code> to <code>EARTH_RADIUS</code> (which obviously won't work for a <code>CGRect</code> of a <code>UIView</code>, which is expecting values between zero and the width/height of the view). </p> <p>I assume the underlying algorithm is one like discussed here: <a href="https://stackoverflow.com/questions/1185408/converting-from-longitude-latitude-to-cartesian-coordinates/1185413#1185413">Converting from longitude\latitude to Cartesian coordinates</a>. I've tried to fix the degrees to radians conversion needed by <code>cos</code> and <code>sin</code>, you still need to scale this and translate it to values appropriate for what portion of the map/radar you're intending to show.</p>

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