如何删除CAShapeLayer沿用户拖动？

我是新来的绘画应用程序，所以请build议我有什么办法删除。

我GOOGLE了我只得到

CGContextSetBlendMode(_context, kCGBlendModeClear); 

但不适用于CAShape层

 UIBezierPath *path = [UIBezierPath bezierPath]; [path moveToPoint:CGPointMake(touchPoint.x,touchPoint.y)]; [path addLineToPoint:CGPointMake(startingPoint.x,startingPoint.y)]; CAShapeLayer *shapeLayer = [CAShapeLayer layer]; shapeLayer.path = [path CGPath]; // shapeLayer.strokeColor =kCGBlendModeClear; if([UIDevice currentDevice].userInterfaceIdiom ==UIUserInterfaceIdiomPad) { shapeLayer.lineWidth = 7.0; } else { shapeLayer.lineWidth = 5.0; } shapeLayer.fillColor = [[UIColor clearColor] CGColor]; [self.layer addSublayer:shapeLayer]; [clearBeizer addObject:shapeLayer]; 

请帮我删除这一层谢谢。