具有malloc'd结构的nsmutableray addobject

我在一段代码上遇到了麻烦。我正在尝试使用addObject方法将cllocationCoordinate2d的实例添加到NSmutable数组中,但每当执行该行时,我的应用程序就会崩溃。这个代码有什么明显的错误吗?

车祸发生在这条线上:

[points addObject:(id)new_coordinate];

多边形:m:

#import "Polygon.h"

@implementation Polygon
@synthesize points;

- (id)init {
    self = [super init];
    if(self) {
        points = [[NSMutableArray alloc] init];
    }
    return self;
}


-(void)addPointLatitude:(double)latitude Longitude:(double)longitude {
    NSLog(@"Adding Coordinate: [%f, %f] %d", latitude, longitude, [points count]);
    CLLocationCoordinate2D* new_coordinate = malloc(sizeof(CLLocationCoordinate2D));
    new_coordinate->latitude = latitude;
    new_coordinate->longitude = longitude;
    [points addObject:(id)new_coordinate];
    NSLog(@"%d", [points count]);
}


-(bool)pointInPolygon:(CLLocationCoordinate2D*) p {
    return true;
}


-(CLLocationCoordinate2D*) getNEBounds {
    ...
}

-(CLLocationCoordinate2D*) getSWBounds {
    ...
}


-(void) dealloc {
    for(int count = 0; count < [points count]; count++) {
        free([points objectAtIndex:count]);
    }

    [points release];
    [super dealloc];
}

@end