List of closest annotations in MapKit - objective-c

Question

I'm developing an iPhone app with annotations on a map, and I've finished inserting all the annotations. The code I've used for all the annotations (x100) is:
CLLocationCoordinate2D theCoordinate1;
theCoordinate1.latitude = 59.92855;
theCoordinate1.longitude = 10.80467;
MyAnnotation* myAnnotation1=[[MyAnnotation alloc] init];
myAnnotation1.coordinate=theCoordinate1;
myAnnotation1.title=#"Økern Senter - DNB";
myAnnotation1.subtitle=#"Økernveien 145, 0580 OSLO";
[mapView addAnnotation:myAnnotation1];
[annotations addObject:myAnnotation1];
What I'm wondering about is how can I get all these locations in a list that shows the closest annotations to the users location?

Answer 1

What you need to do is calculate the distance between the user and the annotations.
First off, in your MyAnnotation, add a variable keeping the distance value:
Add the following to MyAnnotation.h:
#property (nonatomic, assign) CLLocationDistance distance;
and the synthesize to the .m file ofcourse.
Second, in your mapView class (the one keeping the annotations ect) add the following code when you recieve a new location:
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
[...]
for (MyAnnotation *annotation in self.mapView.annotations) {
CLLocationCoordinate2D coord = [annotation coordinate];
CLLocation *anotLocation = [[CLLocation alloc] initWithLatitude:coord.latitude longitude:coord.longitude];
annotation.distance = [newLocation distanceFromLocation:anotLocation];
}
NSArray *sortedArray;
sortedArray = [self.mapView.annotations sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
NSNumber *first = [NSNumber numberWithDouble:[(MyAnnotation*)a distance]];
NSNumber *second = [NSNumber numberWithDouble:[(MyAnnotation*)b distance]];
return [first compare:second];
}];
[...]
}
You can now use the sortedArray as source for a tableView ect, which is sorted according distance from closest to longest distance.
Of course