Multiple paths are not kept on screen

Question

I have an custom UIView. I keep on the lines and points when the finger touches moves. Then I make points to CGPath with this method：

- (void)makeCGPath
{
CGMutablePathRef path = CGPathCreateMutable();

if (lines&& lines.count>0)
{
    for (int i = 0; i < lines.count; i++)
    {
        CGMutablePathRef linePath = CGPathCreateMutable();

        NSArray *tempArray = [lines objectAtIndex:i];
        CGPoint p = [[tempArray objectAtIndex:0]CGPointValue];
        CGPathMoveToPoint(linePath, NULL, p.x, p.y);
        for (int j = 1; j < tempArray.count; j++)
        {
            p = [[tempArray objectAtIndex:j]CGPointValue];
            CGPathAddLineToPoint(linePath, NULL, p.x, p.y);
        }
        CGPathAddPath(path, NULL, linePath);
        CGPathRelease(linePath);



    }
}
if (points&& points.count > 0)
{
    CGMutablePathRef pointPath = CGPathCreateMutable();
    CGPoint p = [[points objectAtIndex:0]CGPointValue];
    CGPathMoveToPoint(pointPath, NULL, p.x, p.y);
    for (int i = 1; i < points.count;i++ )
    {
        p = [[points objectAtIndex:i]CGPointValue];
        CGPathAddLineToPoint(pointPath, NULL, p.x, p.y);
    }
    CGPathAddPath(path, NULL, pointPath);
    CGPathRelease(pointPath);
}


 drawPath = CGPathCreateCopy(path);
 [self setNeedsDisplay];

 [lines removeAllObjects];
 [points removeAllObjects];
}

And my drawRect is look like this follow.

- (void)drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(ctx, 3);
[[UIColor blackColor]set];
CGContextAddPath(ctx, drawPath);
CGContextStrokePath(ctx);
}

It seems so strange that it displays only the last line on the screen. What's wrong with it?

How can I keep all of these paths on screen?

Answer 1

I have the exact same problem. It's not working on iOS 5.0 but it does work on iOS 5.1 and more. I'm still looking for the fix.

UPADTE: I fixed the issue using UIBezierPath. You can draw all your paths using Besier and then convert it to CGPath this way:

UIBezierPath *path = [[UIBezierPath alloc] init];

// Add all the lines you need
[path addLineToPoint:p];

// Or points
[path moveToPoint:p];

// Append paths
[path appendPath:linePath];

// Make a CGPath from UIBezierPath
CGPath myCGPath = path.CGPath;

Try this code, it should work but I haven't tested it:

- (void)makeCGPath
{
    UIBezierPath *path = [[UIBezierPath alloc] init];

    if (lines && lines.count>0)
    {
        for (int i = 0; i < lines.count; i++)
        {
            UIBezierPath *linePath = [[UIBezierPath alloc] init];

            NSArray *tempArray = [lines objectAtIndex:i];
            CGPoint p = [[tempArray objectAtIndex:0]CGPointValue];
            [linePath addLineToPoint:p];
            for (int j = 1; j < tempArray.count; j++)
            {
                p = [[tempArray objectAtIndex:j]CGPointValue];
                [linePath addLineToPoint:p];
            }
            [path appendPath:linePath];
        }
    }

    if (points && points.count > 0)
    {
        UIBezierPath *pointPath = [[UIBezierPath alloc] init];
        CGPoint p = [[points objectAtIndex:0]CGPointValue];
        [pointPath moveToPoint:p];
        for (int i = 1; i < points.count;i++ )
        {
            p = [[points objectAtIndex:i]CGPointValue];
            [pointPath moveToPoint:p];
        }
        [path appendPath:pointPath];
    }


    drawPath = path.CGPath;
    [self setNeedsDisplay];

    [lines removeAllObjects];
    [points removeAllObjects];
}