iOS - MKMapView place annotation by using address instead of lat / long

≡放荡痞女 提交于 2019-11-27 00:05:25

Based on psoft's excellent information, I was able to achieve what I was looking for with this code.

NSString *location = @"some address, state, and zip";
CLGeocoder *geocoder = [[CLGeocoder alloc] init];
            [geocoder geocodeAddressString:location 
                 completionHandler:^(NSArray* placemarks, NSError* error){
                     if (placemarks && placemarks.count > 0) {
                         CLPlacemark *topResult = [placemarks objectAtIndex:0];
                         MKPlacemark *placemark = [[MKPlacemark alloc] initWithPlacemark:topResult];

                         MKCoordinateRegion region = self.mapView.region;
                         region.center = placemark.region.center;
                         region.span.longitudeDelta /= 8.0;
                         region.span.latitudeDelta /= 8.0;

                         [self.mapView setRegion:region animated:YES];
                         [self.mapView addAnnotation:placemark];
                     }
                 }
             ];

Refactored Swift version:

let location = "some address, state, and zip"
let geocoder = CLGeocoder()
geocoder.geocodeAddressString(location) { [weak self] placemarks, error in
    if let placemark = placemarks?.first, let location = placemark.location {
        let mark = MKPlacemark(placemark: placemark)

        if var region = self?.mapView.region {
            region.center = location.coordinate
            region.span.longitudeDelta /= 8.0
            region.span.latitudeDelta /= 8.0
            self?.mapView.setRegion(region, animated: true)
            self?.mapView.addAnnotation(mark)
        }
    }
}
QED

What you're after is called geocoding or forward-geocoding. Reverse-geocoding is the process of converting a lat/long pair to street address.

iOS5 provides the CLGeocoder class for geocoding. MKPlacemark supports reverse-goecoding in iOS >= 3.0. The data involved of course is very large, so your app will generally need network access to the functionality.

A good place to start is Apple's Location Awareness Programming Guide. Also, there are LOTS of questions about this here on SO. https://stackoverflow.com/search?q=geocoding

Good luck!

Swift version

        let location = self.txtLocation.text;
        let geocoder:CLGeocoder = CLGeocoder();
        geocoder.geocodeAddressString(location!) { (placemarks: [CLPlacemark]?, error: NSError?) -> Void in
            if placemarks?.count > 0 {
                let topResult:CLPlacemark = placemarks![0];
                let placemark: MKPlacemark = MKPlacemark(placemark: topResult);

                var region: MKCoordinateRegion = self.mkMapView.region;
                region.center = (placemark.location?.coordinate)!;
                region.span.longitudeDelta /= 8.0;
                region.span.latitudeDelta /= 8.0;
                self.mkMapView.setRegion(region, animated: true);
                self.mkMapView.addAnnotation(placemark);

            }
        }
EEduard

Since iOS 7, placemark.region.center is deprecated. Now needs to use:

region.center = [(CLCircularRegion *)placemark.region center];

You can also read Apple Documentation about this and here too.

Here's another version ...

- Swift 2017 syntax

- Shows a placename for the point, down the bottom

- Choose any size, say 5 km, as the area shown

func map() {
    let 5km:CLLocationDistance = 5000

    let a= "100 smith avenue some town 90210 SD"
    let g = CLGeocoder()

    g.geocodeAddressString(a) { [weak self] placemarks, error in
        if let p = placemarks?.first, let l = placemark.location {

            let p = MKPlacemark(coordinate: l.coordinate, addressDictionary: nil)

            let cr = MKCoordinateRegionMakeWithDistance(l.coordinate, 5km, 5km)
            let options = [
                MKLaunchOptionsMapCenterKey: NSValue(mkCoordinate: cr.center),
                MKLaunchOptionsMapSpanKey: NSValue(mkCoordinateSpan: cr.span)
            ]

            let m = MKMapItem(placemark: p)
            m.name = "Your House"
            m.openInMaps(launchOptions: options)
        }
    }


}

That is not possible. But you can obtain the long/lat from an Address by using the CLGeocoder class.

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