Stripped stroke on NSBezierPath - objective-c

Question

I am trying to draw a simple diagram. I have squares that are connected by lines. The lines are drawn with NSBezierPath's. I am using a random color for the lines so I can follow them. My problem is that the lines change color.
The output -
Code - I removed the lines that draw the squares so it only draws the lines:
- (void)drawRect:(NSRect)dirtyRect
{
// Drawing code here.
[[NSColor whiteColor] setFill];
NSRectFill(dirtyRect);
CGFloat height = 70.0f;
CGFloat yOffset = 20.0f;
NSRect rect = NSMakeRect(50.0f, 50.0f, 200.0f, height);
NSEnumerator *reverseEnumerator = [steps reverseObjectEnumerator];
NSMutableDictionary *rectsByStep = [NSMutableDictionary dictionaryWithCapacity:10];
for( WFGJobStep *step in reverseEnumerator )
{
[[NSColor redColor] setFill];
[rectsByStep setObject:[NSValue valueWithRect:rect] forKey:[NSNumber numberWithInteger:step.step]];
rect.origin.y += height + yOffset;
}
reverseEnumerator = [steps reverseObjectEnumerator];
for( WFGJobStep *step in reverseEnumerator )
{
NSRect stepRect = [[rectsByStep objectForKey:[NSNumber numberWithInteger:step.step]] rectValue];
NSPoint startPoint = NSMakePoint( stepRect.origin.x + stepRect.size.width, stepRect.origin.y);
// draw lines
for( NSNumber *stepNumber in step.nextSteps )
{
//
//
// Line drawing code here
//
//
NSBezierPath * path = [NSBezierPath bezierPath];
[path setLineWidth: 4];
NSRect targetStepRect = [[rectsByStep objectForKey:stepNumber] rectValue];
NSPoint endPoint = NSMakePoint( targetStepRect.origin.x + targetStepRect.size.width, targetStepRect.origin.y + targetStepRect.size.height);
[path moveToPoint:startPoint];
CGFloat controlX = ( startPoint.y - endPoint.y ) * .2 + stepRect.origin.x + stepRect.size.width + 20;
[path curveToPoint:endPoint controlPoint1:NSMakePoint(controlX, startPoint.y) controlPoint2:NSMakePoint(controlX, endPoint.y)];
NSRect square = NSMakeRect( endPoint.x, endPoint.y, 9, 9 );
[path appendBezierPathWithOvalInRect: square];
[[self randomColor] set];
[path stroke];
}
}
}
- (NSColor *)randomColor {
float c[4];
c[0] = (arc4random() / RAND_MAX) * 1;
c[1] = (arc4random() / RAND_MAX) * 1;
c[2] = (arc4random() / RAND_MAX) * 1;
c[3] = 1.0f;
return [NSColor colorWithDeviceRed:c[0] green:c[1] blue:c[2] alpha:c[3]];
}

Answer 1

My issue is that this is in a scoll view and this is my first NSScrollView. I was not aware that as the view scrolls it redraws its subviews. The issue was that I was using a random color for my stroke so that as I scrolled it would randomly change the colors of the lines.