Drawing leaves trails when resizing window - objective-c

Question

I am trying to draw a box in custom view. I have the points for the corners of the box and they are scaled. If I put a small rectangle at each vertex on the box and the resize the window it works perfectly. If I use [path stroke] to draw the lines between the vertices and then resize the window, I end up with a mess as the box is redrawn as the window gets resized, so instead of a single box in a resized window I get all the boxes that were redrawn. I have not found a way to clear the custom view of all the intermediary drawings. Any help would be appreciated. Also, I am really new at this.
#import <Cocoa/Cocoa.h>
#interface PointDisplay : NSView
{
NSBezierPath *pathForLine;
NSMutableArray *pointList;
float originalWidth;
float originalHeight;
}
#end
import "PointDisplay.h"
#implementation PointDisplay
- (id)initWithFrame:(NSRect)frameRect
{
self = [super initWithFrame:frameRect];
if (self)
{
int opts = (NSTrackingActiveAlways | NSTrackingInVisibleRect | NSTrackingMouseEnteredAndExited | NSTrackingMouseMoved);
NSTrackingArea *area = [[NSTrackingArea alloc] initWithRect:[self bounds]
options:opts
owner:self
userInfo:nil];
[self addTrackingArea:area];
pathForLine = [[NSBezierPath alloc] init];
pointList = [[NSMutableArray alloc] init];
NSRect originalRect = [self bounds];
originalWidth = originalRect.size.width;
originalHeight = originalRect.size.height;
}
return self;
}
- (void)drawRect:(NSRect)dirtyRect
{
[super drawRect:dirtyRect];
NSRect myRect = [self bounds];
float widthNow = myRect.size.width;
float heightNow = myRect.size.height;
[[NSColor greenColor] set];
[NSBezierPath fillRect:myRect];
int rectWidth = 10, rectHeight = 10;
float lineWidth = 3.0;
if (pointList.count != 0)
{
NSPoint myPoint = [pointList[0] locationInWindow];
myPoint = [self convertPoint:myPoint fromView:nil];
myPoint.x = (myPoint.x - rectWidth / 2) * widthNow / originalWidth;
myPoint.y = (myPoint.y - rectHeight / 2) * heightNow / originalHeight;
[pathForLine moveToPoint:myPoint];
NSRect anotherRect = NSMakeRect(myPoint.x, myPoint.y, rectWidth, rectHeight);
[[NSColor redColor] set];
[pathForLine setLineWidth:lineWidth + .5 * ((int)lineWidth % 2)];
//[[NSBezierPath bezierPathWithRect:anotherRect] stroke];
for (int i = 1; i < pointList.count; i++)
{
myPoint = [pointList[i] locationInWindow];
myPoint = [self convertPoint:myPoint fromView:nil];
myPoint.x = (myPoint.x - 5) * widthNow / originalWidth;
myPoint.y = (myPoint.y - 5) * heightNow / originalHeight;
anotherRect = NSMakeRect(myPoint.x, myPoint.y, 10, 10);
[pathForLine lineToPoint:myPoint];
[pathForLine stroke];
//[[NSBezierPath bezierPathWithRect:anotherRect] fill];
}
}
}
#pragma mark Mouse events
- (void)mouseUp:(NSEvent *)theEvent
{
[pointList addObject:theEvent];
[self setNeedsDisplay:YES];
}
- (void)mouseExited:(NSEvent *)theEvent
{
[pathForLine closePath];
[pathForLine stroke];
[self setNeedsDisplay:YES];
}
#end