I'm developing an iphone app using mapkit and CLLocationManager.
I put lots of MKPinAnnotationView on map (about 100) and I want to update all callout's subtitle whith user distance when I receive it.
How to do it ?
Thanks
I try this to update subtitle callout with new location but it didn't work well.
In my MyAppDelegate.h
extern NSString * const GMAP_USERLOCATION_CHANGED;
@interface MyAppDelegate : NSObject <UIApplicationDelegate> {
CLLocationManager *locationManager;
CLLocation *userLocation;
}
@property (nonatomic, retain) CLLocationManager *locationManager;
@property (nonatomic, retain) CLLocation *userLocation;
@end
In my MyAppDelegate.m
@implementation MyAppDelegate
NSString * const GMAP_USERLOCATION_CHANGED = @"gMapUserLocationChanged";
@synthesize locationManager, userLocation;
- (void)applicationDidFinishLaunching:(UIApplication *)application
{
userLocation = nil;
[[self locationManager] startUpdatingLocation];
[window addSubview:tabBarController.view];
[window makeKeyAndVisible];
}
#pragma mark -
#pragma mark Core Location delegate
- (CLLocationManager *)locationManager
{
if (locationManager != nil)
{
return locationManager;
}
locationManager = [[CLLocationManager alloc] init];
locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
locationManager.delegate = self;
return locationManager;
}
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
{
self.userLocation = newLocation;
// send notification to defaulcenter
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc postNotificationName:GMAP_USERLOCATION_CHANGED object:self.userLocation];
}
- (void)dealloc {
[window release];
[locationManager release];
[userLocation release];
[super dealloc];
}
@end
I made a customAnnotationView named MyAnnotation.
in MyAnnotation.h :
@interface MyAnnotation : MKPinAnnotationView<MKAnnotation>
{
double longitude;
double latitude;
NSString *title;
NSString *subtitle;
}
@property (nonatomic, retain) NSString *title;
@property (nonatomic, retain) NSString *subtitle;
@property double longitude;
@property double latitude;
@end
in MyAnnotation.m :
#import "MyAnnotation.h"
#import "MyAppDelegate.h"
@implementation MyAnnotation
@synthesize title, subtitle;
@synthesize longitude;
@synthesize latitude;
-(id)initWithAnnotation:(id <MKAnnotation>)annotation reuseIdentifier:(NSString *)reuseIdentifier
{
self = [super initWithAnnotation:annotation reuseIdentifier:reuseIdentifier];
if (self != nil)
{
NSLog(@"add observer");
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc addObserver:self selector:@selector(receivedNewUserLocation:) name:GMAP_USERLOCATION_CHANGED object:nil];
}
return self;
}
- (void)setTitleAndSubtitle
{
[self setTitleAndSubtitle:nil];
}
- (id)setTitleAndSubtitle:(CLLocation*)userLocation
{
CLLocationDistance dist = -1;
if(userLocation)
{
CLLocation *poiLoc = [[CLLocation alloc] initWithLatitude:self.latitude longitude:self.longitude];
dist = [userLocation distanceFromLocation:poiLoc] / 1000;
NSLog(@"distance is now %.f", dist);
}
title = @"the Title of the poi!";
subtitle = [NSString stringWithFormat:@"Distance: %@",
dist > -1 ? [NSString stringWithFormat:@"%.2f km", dist] : @"-"
];
return self;
}
- (void)receivedNewUserLocation:(NSNotification *)userLocationNotification
{
CLLocation *userlocation = (CLLocation*)[userLocationNotification object];
[self setTitleAndSubtitle:userlocation];
}
- (CLLocationCoordinate2D)coordinate;
{
CLLocationCoordinate2D theCoordinate;
theCoordinate.latitude = latitude;
theCoordinate.longitude = longitude;
return theCoordinate;
}
- (NSString *)title
{
return title;
}
- (NSString *)subtitle
{
return subtitle;
}
- (void)dealloc
{
[title release];
[subtitle release];
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc removeObserver:self];
[super dealloc];
}
@end
In the end I use it like that in my MapViewController (I put only the viewForAnnotation delegate method here):
- (MKAnnotationView *)mapView:(MKMapView *)theMapView viewForAnnotation:(id <MKAnnotation>)annotation
{
// if it's the user location, just return nil.
if ([annotation isKindOfClass:[MKUserLocation class]])
return nil;
MyAnnotation *annotationView = nil;
MyAnnotation* myAnnotation = (MyAnnotation *)annotation;
// try to dequeue an existing pin view first
NSString* identifier = @"CustomMapAnnotation";
MyAnnotation *customPinView = (MyAnnotation *)[self.mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
if(nil == customPinView)
{
// if an existing pin view was not available, create one
customPinView = [[[MyAnnotation alloc]
initWithAnnotation:myAnnotation
reuseIdentifier:identifier]
autorelease];
customPinView.animatesDrop = YES;
customPinView.canShowCallout = YES;
}
annotationView = customPinView;
[annotationView setEnabled:YES];
[annotationView setCanShowCallout:YES];
return annotationView;
}
After all of this subtitle is not update after the mkannotation is load on map.... What's wrong ?
thanks for your help...
When you update the title, you should notify the MKAnnotationView to update the callout view, by whichever KVO manner that fits your need best, e.g.:
synthesize or implement setter for title and use
self.title = @"new title";
use explicit KVO notifications
[self willChangeValueForKey:@"title"];
[title release];
title = [newTitle copy];
[self didChangeValueForKey:@"title"];
Ditto for subtitle.