Swift语言 代码添加文本输入框 和 占位文本

 //懒加载文本输入框
    private lazy var textView: UITextView = {
        let textView = UITextView()
        
        textView.font = UIFont.systemFontOfSize(18)
        textView.textColor = UIColor.darkGrayColor()

 //处理键盘，设置键盘的消失模式
        textView.keyboardDismissMode = UIScrollViewKeyboardDismissMode.OnDrag
        
        //设置弹簧效果
        textView.alwaysBounceVertical = true

return textView
        
     }()
    
    //懒加载占位文本
    private lazy var placeHoderLabel: UILabel = UILabel(title: "分享新鲜事...", size: 18, color: UIColor.lightGrayColor())

//设置输入文本框
    private func setTextView() {
        //添加子控件
        view.addSubview(textView)
        textView.backgroundColor = UIColor.randomColor()
   
        //设置约束
        textView.snp_makeConstraints { (make) -> Void in
            make.top.left.right.equalTo(self.view)
            make.height.equalTo(view.bounds.height / 3)
        }
        
        //添加占位文本
        textView.addSubview(placeHoderLabel)
        
        //约束
        placeHoderLabel.snp_makeConstraints { (make) -> Void in
            make.top.equalTo(textView.snp_top).offset(8)
            make.left.equalTo(textView.snp_left).offset(5)
        }
        
    }