let alertView = UIAlertView()
        alertView.title = "系统提示"
        alertView.message = "您确定要离开hangge.com吗？"
        alertView.addButtonWithTitle("取消")
        alertView.addButtonWithTitle("确定")
        alertView.cancelButtonIndex=0
        alertView.delegate=self;
        alertView.show()

func alertView(alertView:UIAlertView,clickedButtonAtIndex buttonIndex: Int){
        if(buttonIndex==alertView.cancelButtonIndex){
            print("点击了取消")
        }
        else
        {
            print("点击了确认")
        }
    }