let bt =UIButton.init(frame:CGRect(x:20, y:250, width:120, height:60))
bt.backgroundColor=UIColor.orange
bt.layer.cornerRadius=10.0
bt.layer.shadowOffset=CGSize(width:1, height:1)
bt.layer.shadowOpacity=0.8
bt.layer.shadowColor=UIColor.green.cgColor
bt.setTitle("搞事情", for: .normal)
self.view.addSubview(bt)
