UIBezierPath gives CGContextRestoreGState error

Question

A simple line over a scrollview :

 UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(1382.0, 144.0)];
    [path addLineToPoint:CGPointMake(1655.0, 152.0)];
     path.lineWidth = 2;
    [path fill];

gives many of these :

CGContextRestoreGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.

for:

CGContextSaveGState ,CGContextSetFlatness,CGContextAddPath,CGContextDrawPath

What is wrong with me ?

EDIT: This also gives a crash:

   UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(1382.0, 144.0)];
    [path addLineToPoint:CGPointMake(1655.0, 152.0)];
    path.lineWidth = 2;

    CAShapeLayer *myLayer = (CAShapeLayer*) self.scroller.layer;
    UIBezierPath *testPath = [UIBezierPath bezierPathWithRect:self.view.bounds];
    [testPath appendPath:path];
    myLayer.path = testPath.CGPath;
    myLayer.fillColor = [UIColor blackColor].CGColor;
    [self.scroller.layer addSublayer:myLayer];


[CALayer setPath:]: unrecognized selector sent to instance

Can you check your scrollView frame when you set the bezier path ? — Michaël Azevedo, Jan 19 '16 at 16:59
that means you don't have a context, when you call the `–fill` method. — holex, Jan 19 '16 at 17:00
Thanks, i think i am missing the point, so what should i do about it? — Curnelious, Jan 19 '16 at 17:00
Maybe your view frame is nul (well, (0,0,0,0)) when the path is added, because your error looks like an invalid context issue. — Michaël Azevedo, Jan 19 '16 at 17:01

score 4 · Accepted Answer · edited May 23 '17 at 11:52

4

The error is saying that you cannot just call fill. That is intended to be used only within a valid context (e.g. in the drawRect of a UIView subclass or inside an image or PDF context). Either create a UIView subclass and implement this in its drawRect or create a CAShapeLayer and set its path property.

See how do you draw a line programmatically from a view controller? for a discussion of these various approaches.

edited May 23 '17 at 11:52

Community

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answered Jan 19 '16 at 17:01

Rob

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Your `CAShapeLayer *myLayer = (CAShapeLayer*) self.scroller.layer;` should be `CAShapeLayer *myLayer = [CAShapeLayer layer];`. You want to create a `CAShapeLayer`, but your code was getting the existing `CALayer`. – Rob Jan 19 '16 at 17:08

UIBezierPath gives CGContextRestoreGState error

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