swift怎么获取touch里的点

override func touchesBegan(touches:Set, withEvent event: UIEvent?) {

if let brush = self.brush {

brush.lastPoint = nil

//之前一直是用这个方法来获取的

//brush.beginPoint = touches.anyObject()!.locationInView(self)

//现在上面那个touches里面没有anyObject()这个方法，所以我们需要做类型转换

brush.beginPoint = (touches as NSSet).anyObject()!.locationInView(self)

}