Drag an annotation pin on a mapview - iphone

Question

The annotation pin is draggable but I couldn't drop it to the destination location. The problem is how could I get the destination location's coordinate where i drop the annotation pin? Any method exist?
Edit 1:
The center of the annotation pin seems never changed where ever I drop the pin.
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)annotationView didChangeDragState:(MKAnnotationViewDragState)newState
fromOldState:(MKAnnotationViewDragState)oldState
{
if (newState == MKAnnotationViewDragStateEnding)
{
NSLog(#"x is %f", annotationView.center.x);
NSLog(#"y is %f", annotationView.center.y);
CGPoint dropPoint = CGPointMake(annotationView.center.x, annotationView.center.y);
CLLocationCoordinate2D newCoordinate = [self.mapView convertPoint:dropPoint toCoordinateFromView:annotationView.superview];
[annotationView.annotation setCoordinate:newCoordinate];
}
}
Edit 2:
Annotation.h
#property (nonatomic,readwrite,assign) CLLocationCoordinate2D coordinate;
Annotation.m
- (void)setCoordinate:(CLLocationCoordinate2D)newCoordinate {
coordinate = newCoordinate;
}
Edit 3:
where ever I drag the pin, the NSLog out put of the droppedAt is always the same.
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)annotationView didChangeDragState:(MKAnnotationViewDragState)newState
fromOldState:(MKAnnotationViewDragState)oldState
{
if (newState == MKAnnotationViewDragStateEnding)
{
CLLocationCoordinate2D droppedAt = annotationView.annotation.coordinate;
NSLog(#"Pin dropped at %f,%f", droppedAt.latitude, droppedAt.longitude);
}
}
Edit 4:
Annotaion.m
#dynamic startAddr;
- (CLLocationCoordinate2D)coordinate
{
coordinate.latitude = [self.startAddr.latitude doubleValue];
coordinate.longitude = [self.startAddr.longitude doubleValue];
return coordinate;
}
- (void)setCoordinate:(CLLocationCoordinate2D)newCoordinate {
//I need to update the self.startAddr.latitude and longitude here. Problem solved.
self.startAddr.latitude = [NSNumber numberWithDouble:newCoordinate.latitude];
self.startAddr.longitude = [NSNumber numberWithDouble:newCoordinate.longitude];
coordinate = newCoordinate;
}

Answer 1

First you have to create a custom annotation like this:
MyAnnotation.h
#import <MapKit/MapKit.h>
#interface MyAnnotation : NSObject <MKAnnotation>{
CLLocationCoordinate2D coordinate;
}
- (id)initWithCoordinate:(CLLocationCoordinate2D)coord;
- (void)setCoordinate:(CLLocationCoordinate2D)newCoordinate;
#end
MyAnnotation.m
#import "MyAnnotation.h"
#implementation MyAnnotation
#synthesize coordinate;
- (NSString *)subtitle{
return nil;
}
- (NSString *)title{
return nil;
}
-(id)initWithCoordinate:(CLLocationCoordinate2D)coord {
coordinate=coord;
return self;
}
-(CLLocationCoordinate2D)coord
{
return coordinate;
}
- (void)setCoordinate:(CLLocationCoordinate2D)newCoordinate {
coordinate = newCoordinate;
}
#end
After that, you just have to use your annotation like this:
// Assuming you have imported MyAnnotation.h and you have a self.map property pointing to a MKMapView
MyAnnotation *myPin = [[MyAnnotation alloc] initWithCoordinate:self.map.centerCoordinate]; // Or whatever coordinates...
[self.map addAnnotation:myPin];
Also, you have to return a view for your annotation. You can do so like this:
- (MKAnnotationView *) mapView: (MKMapView *) mapView viewForAnnotation: (id<MKAnnotation>) annotation {
MKPinAnnotationView *pin = (MKPinAnnotationView *) [self.map dequeueReusableAnnotationViewWithIdentifier: #"myPin"];
if (pin == nil) {
pin = [[[MKPinAnnotationView alloc] initWithAnnotation: annotation reuseIdentifier: #"myPin"] autorelease]; // If you use ARC, take out 'autorelease'
} else {
pin.annotation = annotation;
}
pin.animatesDrop = YES;
pin.draggable = YES;
return pin;
}
Then, once you have adopted the MKMapViewDelegate protocol in your controller, you grab the coordinates of a pin after dragging it like this:
- (void)mapView:(MKMapView *)mapView
annotationView:(MKAnnotationView *)annotationView
didChangeDragState:(MKAnnotationViewDragState)newState
fromOldState:(MKAnnotationViewDragState)oldState
{
if (newState == MKAnnotationViewDragStateEnding)
{
CLLocationCoordinate2D droppedAt = annotationView.annotation.coordinate;
NSLog(#"Pin dropped at %f,%f", droppedAt.latitude, droppedAt.longitude);
}
}

Answer 2

Out of the blue, implement the setCoordinates method of your annotation and make a callBAck when your annotation coordinates have changed
edit : beware of the dragState property of your annotation while its moving.

Answer 3

Don't you wan't to do this :
Setting the annotation delegate,
then
- (void)setCoordinate:(CLLocationCoordinate2D)newCoordinate {
coordinate = newCoordinate;
if (self.delegate respondsToSelector:#selector(mapAnnotationCoordinateHaveChanged))
[self.delegate performSelector(#selector(mapAnnotationCoordinateHaveChanged))];
}
In your delegate :
- (void) mapAnnotationCoordinateHaveChanged{
//some coordinates update code
}

Answer 4

- (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>) annotation
{
MKAnnotationView *a = [ [ MKAnnotationView alloc ] initWithAnnotation:annotation reuseIdentifier:#"currentloc"];
// a.title = #"test";
if ( a == nil )
a = [ [ MKAnnotationView alloc ] initWithAnnotation:annotation reuseIdentifier: #"currentloc" ];
NSLog(#"%f",a.annotation.coordinate.latitude);
NSLog(#"%f",a.annotation.coordinate.longitude);
CLLocation* currentLocationMap = [[[CLLocation alloc] initWithLatitude:a.annotation.coordinate.latitude longitude:a.annotation.coordinate.longitude] autorelease];
[self coordinatesToDMS:currentLocationMap];
MKPinAnnotationView *annView=[[MKPinAnnotationView alloc] initWithAnnotation:a reuseIdentifier:#"currentloc"];
if(a.annotation.coordinate.longitude == mapView.userLocation.coordinate.longitude || a.annotation.coordinate.latitude == mapView.userLocation.coordinate.latitude )
{
if ([annotation isKindOfClass:MKUserLocation.class])
{
//user location view is being requested,
//return nil so it uses the default which is a blue dot...
return nil;
}
//a.image = [UIImage imageNamed:#"userlocation.png"];
//a.pinColor=[UIColor redColor];
}
else
{
// annView.image =[UIImage imageNamed:#"map-pin.png"];
//PinFirst=FALSE;
//annView.pinColor = [UIColor redColor];
// annView.annotation=annotation;
}
annView.animatesDrop = YES;
annView.draggable = YES;
annView.canShowCallout = YES;
return annView;
}
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
NSLog(#"map Drag");
}
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view didChangeDragState:(MKAnnotationViewDragState)newState
fromOldState:(MKAnnotationViewDragState)oldState;
{
NSLog(#"pin Drag");
if (newState == MKAnnotationViewDragStateEnding)
{
CLLocationCoordinate2D droppedAt = view.annotation.coordinate;
NSLog(#"Pin dropped at %f,%f", droppedAt.latitude, droppedAt.longitude);
CLLocation* draglocation = [[[CLLocation alloc] initWithLatitude:droppedAt.latitude longitude:droppedAt.longitude] autorelease];
}
}

Answer 5

Example for Swift 2.2, Xcode 7.3.1:
Create custom class adopting MKAnnotation protocol
(note: Swift doesn't have automatic notification for KVO-compliant properties, so I have added my own - this is not required):
import MapKit
class MyAnnotation: NSObject, MKAnnotation {
// MARK: - Required KVO-compliant Property
var coordinate: CLLocationCoordinate2D {
willSet(newCoordinate) {
let notification = NSNotification(name: "VTAnnotationWillSet", object: nil)
NSNotificationCenter.defaultCenter().postNotification(notification)
}
didSet {
let notification = NSNotification(name: "VTAnnotationDidSet", object: nil)
NSNotificationCenter.defaultCenter().postNotification(notification)
}
}
// MARK: - Required Initializer
init(coordinate: CLLocationCoordinate2D) {
self.coordinate = coordinate
}
}
Declare pin view as draggable:
// MARK: - MKMapViewDelegate Actions
func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView? {
let pinView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: pinViewReuseIdentifier)
pinView.draggable = true
return pinView
}
Now, when the pin is dragged, it invokes the delegate method:
func mapView(mapView: MKMapView, didSelectAnnotationView view: MKAnnotationView)
Here, you can retrieve the new end coordinates.
Alternatively, you could create a userInfo dictionary for the custom annotation's coordinate property's notifications. Observers could then retrieve the values upon receipt of the notification.

Answer 6

In Swift my problem was that the coordinate attribute was a letin my subclass and not a var as it is in the MKAnnotation.
class MyAnnotation : NSObject, MKAnnotation {
let title : String?
let subtitle : String?
var coordinate : CLLocationCoordinate2D
init(title: String, subtitle: String, coordinate: CLLocationCoordinate2D) {
self.title = title
self.subtitle = subtitle
self.coordinate = coordinate
super.init()
}
}