Xcode 1.3 ,I use first instead any object.Cannot invoke>

Cannot invoke 'locationInView' with an argument list of type '(AnyObject!)'

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

var newPoint = touches.first.locationInView(self.drawView)
  lines.append(Line(start: lastPoint, end: newPoint! , color :drawColor))
lastPoint = newPoint

self.setNeedsDisplay()

}