Add Current Location to MKMapRect - iphone

Question

I use this code to show all my annotations on my map:
MKMapRect zoomRect = MKMapRectNull;
for (id <MKAnnotation> annotation in mapView.annotations)
{
MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);
MKMapRect pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0, 1000);
if (MKMapRectIsNull(zoomRect)) {
zoomRect = pointRect;
} else {
zoomRect = MKMapRectUnion(zoomRect, pointRect);
}
}
[mapView setVisibleMapRect:zoomRect animated:YES];
But I also have a "My Location" button on my map-app which when pressed shows my own location.
How do I add my location to the MKMapRect so that it shows all the annotations as well as my own location?

Answer 1

You can use [myMapView setShowsUserLocation: YES]; to show the location of the user (I assume that it is "my location" and that you name your map view "myMapView").
That will show the blue dot, just like the Maps app does. However it will not change the view.
You can recenter the view so that all annotations are visible by creating and setting a new region that spans the max and min longitude and latitude of all the annotations. The code would look something like this.
// Get all the coordinates
NSArray *coordinates = [myMapView valueForKeyPath:#"annotations.coordinate"];
// Longitude and latitude max and min
CLLocationCoordinate2D maxCoord = {-90.0f, -180.0f};
CLLocationCoordinate2D minCoord = {90.0f, 180.0f};
for(NSValue *value in coordinates) {
CLLocationCoordinate2D coord = {0.0f, 0.0f};
// Unpack the NSValue to get the CLLocationCoordinate2D struct inside
[value getValue:&coord];
// Update max and min to
if(coord.longitude > maxCoord.longitude) {
maxCoord.longitude = coord.longitude;
}
if(coord.latitude > maxCoord.latitude) {
maxCoord.latitude = coord.latitude;
}
if(coord.longitude < minCoord.longitude) {
minCoord.longitude = coord.longitude;
}
if(coord.latitude < minCoord.latitude) {
minCoord.latitude = coord.latitude;
}
}
// Create a new region that covers all the annotations
MKCoordinateRegion region = {{0.0f, 0.0f}, {0.0f, 0.0f}};
region.center.longitude = (minCoord.longitude + maxCoord.longitude) / 2.0;
region.center.latitude = (minCoord.latitude + maxCoord.latitude) / 2.0;
region.span.longitudeDelta = (maxCoord.longitude - minCoord.longitude);
region.span.latitudeDelta = (maxCoord.latitude - minCoord.latitude);
region = [myMapView regionThatFits:region];
// Animate to the new region
[myMapView setRegion:region animated:YES];
This works because the blue user location dot is also an annotation. So you may need to update your view for annotations code to account for that, something like.
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation {
MKAnnotationView *view = nil;
if (annotation != mapView.userLocation) {
// Your code here...
}
return view;
}
However, this will not update as the users location update. You will need to call the code that updates the map region yourself. You could either do it only when the user taps the "My Location" button or you could use Core Location to get an event whenever the user has moved enough. Updating the map region every time the user moved a few hundred meters would consume a lot of battery and probably be overkill, depending on your application.