UIBezierPath draw line representation - uiview

Question

I wrote a simple drawing code using UIBezierPath and the -touches... methods of UIView. The drawing works great, but I made some bad experiences.
When I'm painting very slow, it works great. But the more fast I draw, the more edgy the line gets. So how do I like "smooth" them to become less edgy (more points)?
When I use setLineWidth with high line widths, the line become very ugly.
Here is an image to show what ugly actually means:
Why does it draw fat line in that way?!
EDIT: here some code
- (void)drawInRect:(CGRect)rect
{
for(UIBezierPath *path in pathArray) {
[[UIColor blackColor] setStroke];
[path setLineWidth:50.0];
[path stroke];
}
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
startPoint = [[touches anyObject] locationInView:self];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:startPoint];
[path addLineToPoint:[[touches anyObject] locationInView:self]];
if(isDrawing) {
[pathArray removeLastObject];
}
else {
isDrawing = YES;
}
[pathArray addObject:path];
[path close];
[self setNeedsDisplay];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
isDrawing = NO;
}
I hope that somebody can help me with these issues. THANKS a lot, greets, Julian

Answer 1

Mmmmh, I'm not going to address performance issues with your implementation in this thread, but take a look at setNeedsDisplayInRect: in UIView once you get the basics working.
I think you're basically trying to take out the last created path from your array and replace it with a new one for as long as you're moving.
You should try to put a CGMutablePathRef in your array instead (take a look here for that CGMutablePathRef to NSMutableArray).
The basic flow would be something like:
touchesBegan:
Create the CGMutablePathRef
Call moveToPoint
Store in the array
touchesMoved:
Get the lastObject from your array (i.e. the CGMutablePathRef)
Call addLineToPoint
[self setNeedsDisplay]
Then in drawInRect, iterate through your paths and paint them.
Again, this will be slow at first, then you need to optimize. CGLayerRef can help. setNeedsDisplayInRect most definitely will also.