Why are 2 lines rendered with this code (drawRect)?

Question

I was wondering why my window looks like this:

When I resize the window, one line keeps stretching while the other one keeps statically sized and skewed.

The strange part is, that I record the height and width of the window whenever drawRect is called.

At the start of the application, the drawRect method gets called 4 times.

I looked at this and realized it wasn't the actual size, and moved the window size a bit and got real results. What's strange, is how it jumped so fast.

The strange part is how the "ghost" line is still there, I have no idea which one is the ghost! Why? I changed the color of the line which is displayed... and:

The one which is statically displayed is the one which is "generated" using my code each drawRect.

The code I am using for my drawRect:

- (void)drawRect:(NSRect)dirtyRect
{
    NSLog(@"%f, %f", dirtyRect.size.height, dirtyRect.size.width);
    NSBezierPath *line = [NSBezierPath bezierPath];
    [line moveToPoint:NSMakePoint(NSMaxX([self bounds]), NSMaxY([self   bounds]))];
    //Sorry about formatting; SO doesn't make it easy to format.
    [line lineToPoint:NSMakePoint(NSMinX([self bounds]), NSMinY([self bounds]))];
    [line setLineWidth:_lwith]; /// Make it easy to see
    [_lineColor set]; /// Make future drawing the color of lineColor.

    [line stroke];
}

I am asking for a bit of explanation, or just anything that will help! Thanks

Answer 1

Self answered

What did I do?: I had my subclass of NSView inside of another NSView in the storyboard; the child NSView was statically kept at a certain size, while the NSView (parent/window) was moving around freely. Keep in mind, I had my instance of the child NSView saved in my ViewController. My NSView was displaying a line no matter what, and it only changed color if I had the instance of itself.

Make sure you have your storyboard all checked, mine looks like this now:

Notice how neat it is to have only one "graph" view ;)