Swift3.1 UITextView

一、正常写的代码

textFiled.font = UIFont.systemFont(ofSize: 14)
        textFiled.textAlignment = .left
        textFiled.layer.cornerRadius = 6
        textFiled.returnKeyType = UIReturnKeyType.done
        textFiled.isScrollEnabled = true
        textFiled.textColor = UIColor(red: 174, green: 183, blue: 186, alpha: 1)
        textFiled.delegate = self
        textFiled.backgroundColor = UIColor.white

textFiled.snp.makeConstraints { (make) in
            make.left.equalTo(icon.snp.left)
            make.right.equalTo(screen_Witch).offset(-12)
            make.height.equalTo(96)
            make.top.equalTo(title.snp.bottom).offset(12)
        }

二、添加默认文字

// textField里面的默认文字
        textLable.frame = CGRect(x: 10, y: 10, width: 200, height: 20)
        textLable.isEnabled = false
        textLable.text = "输入任务描述"
        textLable.font = UIFont.systemFont(ofSize: 14)
        textLable.textColor = UIColor(red: 174, green: 183, blue: 186, alpha: 1)
        textFiled.addSubview(textLable)

extension LJDescriptionCell:UITextViewDelegate{
    /// 设置文本框当输入的时候，不显示默认文字，当文本内容长度为0的时候，显示默认长度
    func textViewDidChange(_ textView: UITextView) {
        
        let strLenght = NSString(string: textFiled.text)
        
        if strLenght.length == 0{
            textLable.isHidden = false
        }
        else{
            textLable.isHidden = true
        }
    }
}