Use MKLocalSearch to search for locations on a map

Question

I want to use MKLocalSearch for searching in a Map. This functionality is available in iOS 6.1+. Does anybody know how to use this or can anybody give an example of how to use an MKLocalSearch?

MKLocalSearchResponse documentation

Solution 1

The API for MKLocalSearch is fairly easy to understand. At its most basic, you

1. alloc-init an MKLocalSearchRequest
2. Set its naturalLanguageQuery to some search term
3. Use the search request to initialize an MKLocalSearch object
4. Tell the local search to start, passing it a completion handler
5. Do something with the array of MKMapItem objects in the response

   ---

Search for Cafes:

// Create a search request with a string 
MKLocalSearchRequest *searchRequest = [[MKLocalSearchRequest alloc] init];
[searchRequest setNaturalLanguageQuery:@"Cafe"];

// Create the local search to perform the search
MKLocalSearch *localSearch = [[MKLocalSearch alloc] initWithRequest:searchRequest];
[localSearch startWithCompletionHandler:^(MKLocalSearchResponse *response, NSError *error) {
    if (!error) {
        for (MKMapItem *mapItem in [response mapItems]) {
            NSLog(@"Name: %@, Placemark title: %@", [mapItem name], [[mapItem placemark] title]);
        }
    } else {
        NSLog(@"Search Request Error: %@", [error localizedDescription]);
    }
}];

---

You can specify a region for the search like this:

// Search for Cafes in Paris 
MKLocalSearchRequest *searchRequest = [[MKLocalSearchRequest alloc] init];
[searchRequest setNaturalLanguageQuery:@"Cafe"];
CLLocationCoordinate2D parisCenter = CLLocationCoordinate2DMake(48.8566667, 2.3509871);
MKCoordinateRegion parisRegion = MKCoordinateRegionMakeWithDistance(parisCenter, 15000, 15000);
[searchRequest setRegion:parisRegion];

You can also take the region from an MKMapView that the user has zoomed into. This will give better results:

[searchRequest setRegion:self.mapView.region];

---

The response object, an MKLocalSearchResponse, contains an array of MKMapItem objects (mapItems) and an MKCoordinateRegion called boundingRegion, which is a region that contains all the results. You can use it to set a map view to show all results:

[self.mapView setRegion:response.boundingRegion];

---

The array of MKMapItem objects can't be placed on a map (they're used for sending to the Maps app) but each contains a placemark property which can be added to a map:

[localSearch startWithCompletionHandler:^(MKLocalSearchResponse *response, NSError *error) {
    if (!error) {
        for (MKMapItem *mapItem in [response mapItems]) {
            NSLog(@"Name: %@, MKAnnotation title: %@", [mapItem name], [[mapItem placemark] title]);
            NSLog(@"Coordinate: %f %f", [[mapItem placemark] coordinate].latitude, [[mapItem placemark] coordinate].longitude);
            // Should use a weak copy of self
            [self.mapView addAnnotation:[mapItem placemark]];
        }
    } else {
        NSLog(@"Search Request Error: %@", [error localizedDescription]);
    }
}];

Search for Dublin places a pin on the map view and logs:

Name: Dublin, Co. Dublin, MKAnnotation title: Dublin, Co. Dublin, Ireland
Coordinate: 53.344104 -6.267494

---

There are a load of extra details in the returned objects, especially if you search for businesses. Here are a few:

[localSearch startWithCompletionHandler:^(MKLocalSearchResponse *response, NSError *error) {
    if (!error) {
        NSLog(@"Results: %@", [response mapItems]);
        MKMapItem *mapItem = [[response mapItems] objectAtIndex:0];
        NSLog(@"Name:%@ Phone:%@ URL:%@", [mapItem name], [mapItem phoneNumber], [mapItem url]);
        NSLog(@"Placemark: %@", [mapItem placemark]);
        MKPlacemark *placemark = [mapItem placemark];
        NSLog(@"Placemark Address: %@", [placemark addressDictionary]);
        MKCoordinateRegion boundingRegion = [response boundingRegion];
        NSLog(@"Bounds: %f %f", boundingRegion.span.latitudeDelta, boundingRegion.span.longitudeDelta);
    }

Solution 2

Here is an example that search for cafes in a radius of 1 km around a given location :

MKLocalSearchRequest *request = [[MKLocalSearchRequest alloc] init];
CLLocationCoordinate2D location = CLLocationCoordinate2DMake(11.567898, 104.894430);
request.naturalLanguageQuery = @"cafe";
request.region = MKCoordinateRegionMakeWithDistance(location, 1000, 1000);
MKLocalSearch *search = [[MKLocalSearch alloc] initWithRequest:request];
[search startWithCompletionHandler:^(MKLocalSearchResponse *response, NSError *error){
    for (MKMapItem *item in response.mapItems) {
        NSLog(@"%@", item.name);
    }
}];

Please note than when the search is unsuccessful, it does not return an empty list, but an error with domain MKErrorDomain and code 4.