Error with finding area of ​​the intersection of two rectangles (objective-c) -

i make program, find area of ​​the intersection of 2 rectangles. have height, width , coordinates of rectangles.

but wont work! xcode terminates program "thread 1: signal sigabrt" on line (rectangle.m):

reswidth = (origin.x + width) - (second.origin.x + second.width);

so, here's code:

main.m:

#import <foundation/foundation.h> #import "rectangle.h" #import "xypoint.h"  int main(int argc, const char * argv[]) {      nsautoreleasepool * pool = [nsautoreleasepool new];     rectangle *myrect1 = [rectangle new];     rectangle *myrect2 = [rectangle new];     xypoint *temp = [xypoint new];      [temp setx: 200 andy: 420];     [myrect1 setorigin:temp];    [temp setx: 400 andy: 300];    [myrect2 setorigin:temp];    [temp dealloc];     [myrect1 setwidth:250 andheight:75];    [myrect2 setwidth:100 andheight:180];     double print = [myrect1 intersect:myrect2];     nslog(@"%g", print);     [pool drain];     return 0; 

}

rectangle.h:

#import <foundation/foundation.h> #import "xypoint.h"  @interface rectangle : nsobject { double width; double height; xypoint *origin; }  @property double width, height;  -(xypoint *) origin; -(void) setorigin: (xypoint *) pt; -(void) setwidth: (double) w andheight: (double) h; -(double) area; -(double) perimeter; -(double) intersect: (rectangle *) second;  @end 

rectangle.m:

#import "rectangle.h"  @implementation rectangle  @synthesize width, height;  -(void) setorigin:(xypoint *)pt {     origin = [[xypoint alloc] init];     [origin setx: pt.x andy: pt.y]; }  -(void) setwidth: (double) w andheight: (double) h {     width = w;     height = h; }  -(double) area {     return width * height; }  -(double) perimeter {     return (width + height) * 2; }  -(double) intersect:(rectangle *) second {     double result,reswidth,resheight;     reswidth = (origin.x + width) - (second.origin.x + second.width);     if (reswidth<0) reswidth *= -1;     resheight = (origin.y + height) - (second.origin.y + second.height);     if (resheight<0) resheight *= -1;     result = reswidth * resheight;     if (result<0) result *= -1;     return result; } @end 

xypoint.h:

#import <foundation/foundation.h>  @interface xypoint : nsobject {     double x;     double y; }  @property double x,y;  -(void) setx:(double) xval andy: (double) yval;  @end 

xypoint.m:

#import "xypoint.h"  @implementation xypoint  @synthesize x,y;  -(void) setx:(double) xval andy: (double) yval {     x=xval;     y=yval; }  @end 

thanks!!!!

you did not implement method -(xypoint*) origin in rectangle class, crash when second.origin. make origin property in rectangle class , should work. don't use new method much, it's bad practice , stops seeing other init methods might implemented