UIBezierPath 删除问题 [英] UIBezierPath Removal Issue

问题描述

我正在尝试制作一个球从用户绘制的线中弹起的游戏.绘制线的代码包含在下面并且工作正常，但是一旦球与线接触或玩家绘制新线，我将如何移除线?

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];

提前致谢！

推荐答案

当你这样说时:

[self.view.layer addSublayer:shapeLayer];

...也保持对那个形状层的引用.例如，您可能有一个属性 currentShapeLayer:

...also keep a reference to that shape layer. For example, you might have a property currentShapeLayer:

self.currentShapeLayer = shapeLayer;

既然您有了参考，就可以轻松删除图层:

Now that you have a reference, you can easily remove the layer:

[self.currentShapeLayer removeFromSuperlayer];

iOS 编程就是保留对您知道以后需要的东西的引用.如果路径更多，意味着更多的形状层，您将需要一种更复杂、更智能的方式来区分您要删除哪个和哪个.

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.

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