问题
I am trying to make a game where a ball is bouncing off a user drawn line. The code for drawing the line is included below and works fine but how would I remove the line once the ball makes contact with it or the player draws a new line?
path = [UIBezierPath bezierPath];
// Start Coords of Line
[path moveToPoint:CGPointMake(pos2x, pos2y)];
[path addLineToPoint:CGPointMake(pos1x, pos1y)];
// End Coords of Line
CAShapeLayer *shapeLayer = [CAShapeLayer layer];
shapeLayer.path = [path CGPath];
shapeLayer.strokeColor = [[UIColor whiteColor] CGColor];
shapeLayer.lineWidth = 3.0;
shapeLayer.fillColor = [[UIColor clearColor] CGColor];
[self.view.layer addSublayer:shapeLayer];
Thanks in advance!
回答1:
When you say this:
[self.view.layer addSublayer:shapeLayer];
...also keep a reference to that shape layer. For example, you might have a property currentShapeLayer:
self.currentShapeLayer = shapeLayer;
Now that you have a reference, you can easily remove the layer:
[self.currentShapeLayer removeFromSuperlayer];
Programming iOS is all about keeping references to things you know you'll need later on. If there are more paths, meaning more shape layers, you will need a more complex, intelligent way of distinguishing which is which and which one you want to remove.
来源：https://stackoverflow.com/questions/23507359/uibezierpath-removal-issue