How can I update position of an already drawn CGPath
/UIBezierPath
on a view? I would like to move or change a path's position and then perhaps call the drawInRect
method to just render the path again.
From your question it sounds like you are drawing the path using Core Graphics inside drawRect:
(as compared to using a CAShapeLayer
) so I'll explain the version first.
You can create a new path by transforming another path. A translation transform moves the transformed object a certain distance in x and y. So using a translation transform you can move your existing path a certain number of points in both x and y.
CGAffineTransform translation = CGAffineTransformMakeTranslation(xPixelsToMove,
yPixelsToMove);
CGPathRef movedPath = CGPathCreateCopyByTransformingPath(originalCGPath,
&translation);
Then you could use the movedPath
to draw the same way you are already doing.
You could also change modify the same path
yourPath = CGPathCreateCopyByTransformingPath(yourPath,
&translation);
and simply redraw it.
If you are using a shape layer, moving it is even easier. Then you only have to change the position of the layer using the position
property.
If you want to use a shape layer you can simply create a new CAShapeLayer and set its path to be your CGPath. You will need QuartzCore.framework for this since CAShapeLayer is part of Core Animation.
CAShapeLayer *shape = [CAShapeLayer layer];
shape.path = yourCGParth;
shape.fillColor = [UIColor redColor].CGColor;
[someView.layer addSublayer:shape];
Then to move the shape you simply change its position.
shape.position = thePointYouWantToMoveTheShapeTo;