Encoding a CLLocationcoordinate2D - objective-c

Question

I am trying to encode annotations that are on a map, but I read that I am not able to encode CLLocationcoordinate2D variables. Does anyone know how I can solve this? Here is some code.
This is where I drop the pins:
- (void)press:(UILongPressGestureRecognizer *)recognizer {
CGPoint touchPoint = [recognizer locationInView:_worldView];
CLLocationCoordinate2D touchMapCoordinate = [_worldView convertPoint:touchPoint toCoordinateFromView:_worldView];
geocoder = [[CLGeocoder alloc]init];
CLLocation *location = [[CLLocation alloc]initWithCoordinate:touchMapCoordinate
altitude:CLLocationDistanceMax
horizontalAccuracy:kCLLocationAccuracyBest
verticalAccuracy:kCLLocationAccuracyBest
timestamp:[NSDate date]];
[geocoder reverseGeocodeLocation:location
completionHandler:^(NSArray *placemarks, NSError *error) {
//NSLog(#"reverseGeocoder:completionHandler: called");
if (error) {
//NSLog(#"Geocoder failed with error: %#", error);
} else {
CLPlacemark *place = [placemarks objectAtIndex:0];
geocodedAddress = [NSString stringWithFormat:#"%# %#, %# %#", [place subThoroughfare], [place thoroughfare], [place locality], [place administrativeArea]];
if (UIGestureRecognizerStateBegan == [recognizer state]) {
value = [number intValue];
number = [NSNumber numberWithInt:value + 1];
_addressPin = [[MapPoint alloc]initWithAddress:geocodedAddress coordinate:touchMapCoordinate
title:geocodedAddress identifier:number];
NSLog(#"The identifier is %#", number);
[[Data singleton].annotations addObject:_addressPin];
[_worldView addAnnotation:_addressPin];
NSLog(#"The number of pins in the annotation array is: %u",[Data singleton].annotations.count);
}
}
}];
}
Here is my class that conforms to the MKAnnotation protcol:
#import <CoreLocation/CoreLocation.h>
#import <MapKit/MapKit.h>
#interface MapPoint : NSObject <MKAnnotation, NSCoding>
{
}
- (id)initWithAddress:(NSString*)address
coordinate:(CLLocationCoordinate2D)coordinate
title:(NSString *)t
identifier:(NSNumber *)ident;
//This is a required property from MKAnnotation
#property (nonatomic, readonly) CLLocationCoordinate2D coordinate;
//This is an optional property from MKAnnotataion
#property (nonatomic, copy) NSString *title;
#property (nonatomic, readonly, copy) NSString *subtitle;
#property (nonatomic) BOOL animatesDrop;
#property (nonatomic) BOOL canShowCallout;
#property (copy) NSString *address;
#property (copy) NSNumber *identifier;
#property (nonatomic, copy) NSString *imageKey;
#property (nonatomic, copy) UIImage *image;
#end
import "MapPoint.h"
#implementation MapPoint
#synthesize title, subtitle, animatesDrop, canShowCallout, imageKey, image;
#synthesize address = _address, coordinate = _coordinate, identifier = _indentifier;
-(id)initWithAddress:(NSString *)address
coordinate:(CLLocationCoordinate2D)coordinate
title:(NSString *)t
identifier:(NSNumber *)ident {
self = [super init];
if (self) {
_address = [address copy];
_coordinate = coordinate;
_indentifier = ident;
[self setTitle:t];
NSDate *theDate = [NSDate date];
subtitle = [NSDateFormatter localizedStringFromDate:theDate
dateStyle:NSDateFormatterShortStyle
timeStyle:NSDateFormatterShortStyle];
}
return self;
}
- (void)encodeWithCoder:(NSCoder *)aCoder {
[aCoder encodeObject:_address forKey:#"address"];
[aCoder encodeObject:title forKey:#"title"];
[aCoder encodeObject:_indentifier forKey:#"identifier"];
}
- (id)initWithCoder:(NSCoder *)aDecoder {
self = [super init];
if (self) {
[self setAddress:[aDecoder decodeObjectForKey:#"address"]];
}
return self;
}
#end

Answer 1

Just encode the two fields of the CLLocationCoordinate2D value.
[aCoder encodeDouble:_coordinate.latitude forKey:#"latitude"];
[aCoder encodeDouble:_coordinate.longitude forKey:#"longitude"];

Answer 2

NSValue is NSCoding compliant. You can box your CLLocationcoordinate2D variable in an NSValue object:
[coder encodeObject:[NSValue valueWithMKCoordinate:coordinate] forKey:#"coordinate"]

Answer 3

The CLLocationCoordinate2D's latitude and longitude are of type CLLocationDegrees which is, essentially, a fancy way of saying double.
This is how you can encode and decode them:
NSString *const kPinCoordinateLatitudeKey = #"kPinCoordinateLatitudeKey";
NSString *const kPinCoordinateLongitudeKey = #"kPinCoordinateLongitudeKey";
- (void)encodeWithCoder:(NSCoder *)encoder
{
[encoder encodeDouble:self.coordinate.latitude forKey:kPinCoordinateLatitudeKey];
[encoder encodeDouble:self.coordinate.longitude forKey:kPinCoordinateLongitudeKey];
}
- (id)initWithCoder:(NSCoder *)decoder
{
if((self = [super init])) {
CLLocationDegrees latitude = [decoder decodeDoubleForKey:kPinCoordinateLatitudeKey];
CLLocationDegrees longitude = [decoder decodeDoubleForKey:kPinCoordinateLongitudeKey];
_coordinate = CLLocationCoordinate2DMake(latitude, longitude);
}
return self;
}

Answer 4

I decided to encode use a CLLocation property handle this situation, which conforms to NSSecureCoding.
If you need to convert to or from a CLLocationCoordinate2D:
// Coordinate to Location
CLLocationCoordinate2D coord;
CLLocation *loc = [[CLLocation alloc] initWithLatitude:coord.latitude
longitude:coord.longitude];
// Location to Coordinate
CLLocationCoordinate2D coord = loc.coordinate;