MKMapView does not move and zoom to search results - ios

Question

I'm implementing search in my MKMapView and I've faced two problems:
When I perform search, location appears in the result and map moves to the found location only after I start to move to the destination. This happens, when the search results are out of the view bounds. If they are inside of the map view bounds or near them it's fine.
It "hops" all the time from one search result to another or to the user's location. I don't expect such behaviour from it.
I've tried several things and I suppose, that the problem is in: didAddAnnotationViews:
[self.locationManager stopUpdatingLocation];
MKAnnotationView *annotationView = [views objectAtIndex:0];
NSLog(#"_Here_ %#", [views description]);
id<MKAnnotation> mp = [annotationView annotation];
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance([mp coordinate], 250, 250);
[mv setRegion:region animated:YES];
[self.mapView selectAnnotation:mp animated:YES];
Though, I also thought that the problem is in didUpdateToLocation, so I disable updating after the first pin is drop (by search or by tap):
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation {
double miles = 0.3;
double scalingFactor =
ABS( cos(2 * M_PI * newLocation.coordinate.latitude /360.0) );
MKCoordinateSpan span;
span.latitudeDelta = miles/69.0;
span.longitudeDelta = miles/( scalingFactor*69.0 );
MKCoordinateRegion region;
region.span = span;
region.center = newLocation.coordinate;
[self.mapView setRegion:region animated:YES];
self.mapView.showsUserLocation = YES;
}
Finally, search method:
-(void)searchBarSearchButtonClicked:(UISearchBar *)theSearchBar
{
MKLocalSearchRequest *searchRequest = [[MKLocalSearchRequest alloc] init];
[searchRequest setNaturalLanguageQuery:theSearchBar.text];
searchRequest.region = MKCoordinateRegionMakeWithDistance(self.mapView.userLocation.coordinate, 1000, 1000);
MKLocalSearch *localSearch = [[MKLocalSearch alloc] initWithRequest:searchRequest];
[localSearch startWithCompletionHandler:^(MKLocalSearchResponse *response, NSError *error) {
if (!error) {
NSMutableArray *annotations = [NSMutableArray array];
[response.mapItems enumerateObjectsUsingBlock:^(MKMapItem *item, NSUInteger idx, BOOL *stop) {
for (id<MKAnnotation>annotation in self.mapView.annotations)
{
if (annotation.coordinate.latitude == item.placemark.coordinate.latitude &&
annotation.coordinate.longitude == item.placemark.coordinate.longitude)
{
return;
}
}
MKPointAnnotation *addAnnotation = [[MKPointAnnotation alloc] init];
addAnnotation.title = [item.placemark.addressDictionary objectForKey:#"Street"];
addAnnotation.coordinate = item.placemark.coordinate;
[annotations addObject:addAnnotation];
}];
for (id<MKAnnotation>annotation in self.mapView.annotations) {
[self.mapView removeAnnotation:annotation];
}
[self.mapView addAnnotations:annotations];
} else {
NSLog(#"Search Request Error: %#", [error localizedDescription]);
}
}];
//Hide the keyboard.
[self.searchBar resignFirstResponder];
}
My aim is to create a MapView, where user can pin the location by tap or via search and, obviously, see the search result.

Answer 1

For the first problem:
When I perform search, location appears in the result and map moves to
the found location only after I start to move to the destination. This
happens, when the search results are out of the view bounds. If they
are inside of the map view bounds or near them it's fine.
This happens because you are moving the map to the annotations found (at least the first one) in the didAddAnnotationViews delegate method.
But that delegate method is only called when an annotation is in the visible area. If an annotation is added to the map but it's not in the visible area (yet), viewForAnnotation won't get called and therefore didAddAnnotationViews won't get called.
Then, when you manually move the map, the annotations that were added start coming into the visible area and then the delegate method gets called and suddenly the map jumps to one of those annotations.
Don't call setRegion inside the didAddAnnotationViews delegate method.
Sometimes, doing so can also cause an endless cycle of viewForAnnotation and didAddAnnotationViews calls because when the region is changed, it causes other annotations to come into view that weren't previously, so viewForAnnotation gets called and then didAddAnnotationViews gets called, and so on.
Instead, set the region right after you call addAnnotations: (or better, just call showAnnotations:) in the searchBarSearchButtonClicked: method.
I would also remove the call to stopUpdatingLocation from didAddAnnotationViews. You probably don't even need the location manager at all if you set the map's showsUserLocation to YES.
For the second problem:
It "hops" all the time from one search result to another or to the
user's location. I don't expect such behaviour from it.
This is also partly due to calling setRegion in didAddAnnotationViews but also because setRegion is called in didUpdateToLocation.
So for the reason described for the first problem, the two delegate methods and the user's manual movements are fighting with each other and the map ends up hopping around.
Don't call setRegion in the didUpdateToLocation method (or, call it once by keeping track in a BOOL whether you've already zoomed to the user location or not).
Not affecting the behavior, but setting showsUserLocation to YES in the didUpdateToLocation doesn't make sense. Why not set this in viewDidLoad or turn it on in the storyboard/xib?
Also, there's no need to calculate the region span manually like that (it's better to let the MapKit do that work for you). Just convert the miles to meters and call MKCoordinateRegionMakeWithDistance.