Question

I’ve been trying to get rid of memory leaks in mapview. I am using custom map pin class.
Everything works, but problem is – I need to filter mapview results. when i remove all mapview annotations – and add filtered results – performance tool finds leaks. but in this mapPin class I am using are used autorelease, so they should be released, but they aren’t. what am I doing wrong?

MapPin.h

#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
#import <MapKit/MKMapView.h>
#import <MapKit/MKAnnotation.h>

@interface MapPin : NSObject<MKAnnotation> {
    CLLocationCoordinate2D coordinate;
    NSString * picture;
    NSInteger tag_number;
}

@property (nonatomic,assign) CLLocationCoordinate2D coordinate;
@property (nonatomic, copy) NSString *title;
@property (nonatomic, copy) NSString *subtitle;


- (id) initWithCoordinate:(CLLocationCoordinate2D) coord;
- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title;
- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title subtitle:(NSString *) subtitle;
- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title subtitle:(NSString *) subtitle image:(NSString *) pic;
- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title subtitle:(NSString *) subtitle image:(NSString *) pic num:(NSInteger) number;
- (void) setPic:(NSString *) picture;
- (NSString* ) getPic;

- (void) setNum:(NSInteger) tag_number;
- (NSInteger ) getNum;

@end

MapPin.m

#import "MapPin.h"


@implementation MapPin

@synthesize coordinate = _coordinate;
@synthesize title = _title;
@synthesize subtitle = _subtitle;


- (id) initWithCoordinate:(CLLocationCoordinate2D) coord
{
    return [self initWithCoordinate:coord title:@""];
}

- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title {
    return [self initWithCoordinate:coord title:title subtitle:@""];

}
- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title subtitle:(NSString *) subtitle {
    return [self initWithCoordinate:coord title:title subtitle:subtitle image:@""];}

- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title subtitle:(NSString *) subtitle image:(NSString *) pic{
    MapPin * me = [[[MapPin alloc] init] autorelease];
    me.coordinate = coord;
    me.title = title;
    me.subtitle = subtitle;

    [me setPic:pic];

    return me;
}

- (id) initWithCoordinate:(CLLocationCoordinate2D) coord title:(NSString *) title subtitle:(NSString *) subtitle image:(NSString *) pic num:(NSInteger) number{
    MapPin * me = [[[MapPin alloc] init] autorelease];
    me.coordinate = coord;
    me.title = title;
    me.subtitle = subtitle;

    [me setPic:pic];
    [me setNum:number];
    return me;
}

- (void) setPic:(NSString*) pic {
    picture = pic;
}

- (NSString * ) getPic{
    return picture;
}

- (void) setNum:(NSInteger) number {
    tag_number = number;

}

- (NSInteger ) getNum{
    return tag_number;
}

@end

Answer 1

I have been using cutom map pin created by Mayur Birari, which i tweaked a little bit, to support custom map pin images and id’s.

CustomMapPin.h

#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>

@interface CustomMapPin : NSObject<MKAnnotation> {

    CLLocationCoordinate2D  coordinate;
    NSString*               title;
    NSString*               subtitle;

    NSString*               pic;
    NSInteger               tag_number;

}

@property (nonatomic, assign)   CLLocationCoordinate2D  coordinate;
@property (nonatomic, copy)     NSString*               title;
@property (nonatomic, copy)     NSString*               subtitle;
@property (nonatomic, copy)     NSString*               pic;
@property (nonatomic)           NSInteger               tag_number;


@end

CustomMapPin.m

#import "CustomMapPin.h"


@implementation CustomMapPin

@synthesize title;
@synthesize subtitle;
@synthesize coordinate;
@synthesize pic;
@synthesize tag_number;


- (void)dealloc 
{
    self.title = nil;
    self.pic = nil;
    self.subtitle = nil;
    [super dealloc];
}

@end

and using it in class like this:

CLLocationCoordinate2D pinlocation;

in a loop I set up required values and create a map pin:

pinlocation.latitude = ...;

pinlocation.longitude = ...;

NSInteger pinID = ....;


CustomMapPin* customMapPin=[[CustomMapPin alloc] init];

customMapPin.coordinate=(CLLocationCoordinate2D
    {pinlocation.latitude,pinlocation.longitude};

customMapPin.title=@"title";

customMapPin.subtitle=@"subtitle";

customMapPin.pic = @"customImageName";

customMapPin.tag_number = pinId;


[mapView addAnnotation:customMapPin];

Setting up custom image:

- (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>) annotation
{
    if ([annotation isKindOfClass: [CustomMapPin class]]) 
    {
        CustomMapPin * a = annotation;

        [annView setImage:[UIImage imageNamed:a.pic]];
    }
}

Getting pin id on callout:

- (void)mapView:(MKMapView *)mp annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
    CustomMapPin * v = (CustomMapPin *) view.annotation;

   int tagNumber = v.tag_number;

   ....
}

and finally – in my project It was required to have filter buttons – so I needed to remove all pins, and add required. By default calling mapview to remove all annotations created memory leaks. So when I need to clear mapview from annotations, I call this function:

- (void)removeAnnotations
{
    NSMutableArray *toRemove = [NSMutableArray arrayWithCapacity:[mapView.annotations count]];

    for (id annotation in mapView.annotations)
    {
        if (annotation != mapView.userLocation)
        {
            [toRemove addObject:annotation];
        }
    }

    [mapView removeAnnotations:toRemove];

    for(int i = 0; i < [toRemove count]; i++)
    {
        CustomMapPin * a = [toRemove objectAtIndex:i];

        [a release];

        a = nil;
    }
}

Hope this helps
Happy coding! 🙂