一、问题

最近在自定view时候，遇到一个问题，view本身没有错误，app运行起来界面也很正常，但在xml编写引入自定view时，导致整个布局不能预览

下面是我写的代码

class CustomTitleBarView (context: Context?, attrs: AttributeSet?) :
    RelativeLayout(context, attrs, 0), LifecycleEventObserver {
    private val layoutBack: RelativeLayout by lazy { findViewById<RelativeLayout>(R.id.layout_back) }
    private val ivBack: ImageView by lazy { findViewById<ImageView>(R.id.iv_back) }
    private val ivHeat: ImageView by lazy { findViewById<ImageView>(R.id.iv_heat) }
    private val tvHeart: TextView by lazy { findViewById<TextView>(R.id.tv_heart) }
    private val ivGold: ImageView by lazy { findViewById<ImageView>(R.id.iv_gold) }
    private val tvGold: TextView by lazy { findViewById<TextView>(R.id.tv_gold) }
    private val ivHome: ImageView by lazy { findViewById<ImageView>(R.id.iv_home) }


    //点击个人信息
    var clickHomeInfoListener: () -> Unit = {

    }
    //点击返回
    var clickBackListener: () -> Unit ={

    }
    init {
        LayoutInflater.from(context).inflate(R.layout.custom_title_bar, this)
        val typedArray = context?.obtainStyledAttributes(attrs, R.styleable.CustomTitleBarView)
        val leftDrawable = typedArray?.getDrawable(R.styleable.CustomTitleBarView_bar_left_drawable)
        val rightDrawable = typedArray?.getDrawable(R.styleable.CustomTitleBarView_bar_right_drawable)
        typedArray?.recycle()
        if (leftDrawable != null){
            ivBack.setImageDrawable(leftDrawable)
            layoutBack.visibility = View.VISIBLE
        }else{
            layoutBack.visibility = View.GONE
        }
        if (rightDrawable != null){
            ivHome.setImageDrawable(rightDrawable)
            ivHome.visibility = View.VISIBLE
        }else{
            ivHome.visibility = View.GONE
        }
        refreshData()
        clickListener()
        TitleBarHelper.putView(this.hashCode(),this)
        
        (context as AppCompatActivity).lifecycle.addObserver(this)
    }

    private fun clickListener(){
        ivHome.setOnClickListener {
            UserInfoActivity.startAction(context as Activity)
        }
        layoutBack.setOnClickListener {
            (context as Activity).finish()
        }
    }


    /**
     * 动态设置用户红心和金币
     */
    fun setGoldData(heart: String?,gold: String?){
        if (heart == null || gold == null){
            return
        }
        GoldConfig.gold = gold
        GoldConfig.heart = heart
        refreshData()
    }

    fun refreshData(){
        tvHeart.text = GoldConfig.heart
        tvGold.text = GoldConfig.gold
    }

    override fun onStateChanged(source: LifecycleOwner, event: Lifecycle.Event) {
        when(event){
            Lifecycle.Event.ON_DESTROY ->{
                TitleBarHelper.removeView(this.hashCode())
            }
            else -> {

            }
        }
    }
}

二、原因

具体是下面这个方法在init初始化调用，导致不能在xml里面预览，但本身代码可以运行，不会出错。网上查阅资料，是这部分逻辑需要设备支持（俺很懵），在xml中就无法预览。

(context as AppCompatActivity).lifecycle.addObserver(this)

三、解决方法

解决也简单，使用isInEditMode()做下判断，如果是预览，直接不执行

if (!isInEditMode){
    (context as AppCompatActivity).lifecycle.addObserver(this)
}