由于产品是个果婊，有时候为了统一app风格，需要被迫使用ios风格的系统控件，比较常见的就是ios 的底部弹出菜单，在网上找了很久都没有找到还原度很高的，就自己动手写了，为了以防万一以后再有这类需求，这里把大致实现思路和代码献上，有需要的自己copy就行了。

成品图：

UI层级

具体都写在图上了，考虑到性能因素，viewGroup继承自FrameLayout,contentGroup、menuList继承自LinearLayout、CancelButton继承自TextView。

核心思想

• 采用伪Build模式编写，之所以说伪Build是因为没有严格按照模式框架来编写，但是对外调用和Build相似。
• 运用了Toast模式，直接将布局添加到Window下DecorView中，可以在任意Activity中调用，不需要改动原本View或者进行View绑定。

源代码

class IosBottomListWindow(private val activity: Activity) {
    private val shadowMax = 0xa0
    private var majorTitle: TextView? = null
    private var title: TextView? = null
    private val viewGroup: FrameLayout
    private val contentGroup: LinearLayout
    private val menuList: LinearLayout
    private val commonMargin = dpToPx(10f, activity).toInt()
    private val itemMargin = dpToPx(16f, activity).toInt()
    private var contentLayoutHeight = 0

    var isShow = false

    init {
        viewGroup = initViewGroup()
        contentGroup = initContentGroup()
        menuList = initMenuList()
        viewGroup.addView(contentGroup)
        contentGroup.addView(menuList)
    }

    fun show() {
        if (!isShow) {
            (activity.window.decorView as ViewGroup).addView(viewGroup)
            contentGroup.apply {
                post {
                    contentLayoutHeight = measuredHeight
                    translationY = contentLayoutHeight.toFloat()
                    visibility = View.VISIBLE
                    startAnimator(true)
                }
            }
            isShow = true
        }
    }

    fun dismiss() {
        if (isShow) {
            startAnimator(false, object : SimpleAnimListener() {
                override fun onAnimationEnd(animation: Animator?) {
                    (activity.window.decorView as ViewGroup).removeView(viewGroup)
                }
            })
            isShow = false
        }
    }

    /**
     * 设置主标题
     */
    fun setMajorTitle(text: String): IosBottomListWindow {
        majorTitle = TextView(activity).apply {
            layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
                    LinearLayout.LayoutParams.WRAP_CONTENT).apply {
                val margin = dpToPx(20f, activity).toInt()
                if (title == null) {
                    setMargins(0, margin, 0, margin)
                } else {
                    setMargins(0, margin, 0, 0)
                }
            }
            setTextSize(TypedValue.COMPLEX_UNIT_SP, 14f)
            setTextColor(Color.parseColor("#8f8f8f"))
            typeface = Typeface.DEFAULT_BOLD
            setText(text)
        }
        menuList.addView(majorTitle, 0)
        return this
    }

    /**
     * 设置副标题
     */
    fun setTitle(text: String): IosBottomListWindow {
        title = TextView(activity).apply {
            layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
                    LinearLayout.LayoutParams.WRAP_CONTENT).apply {
                val margin = dpToPx(20f, activity).toInt()
                if (majorTitle == null) {
                    setMargins(0, margin, 0, margin)
                } else {
                    setMargins(0, 0, 0, margin)
                }
            }
            setTextSize(TypedValue.COMPLEX_UNIT_SP, 14f)
            setTextColor(Color.parseColor("#8f8f8f"))
            setText(text)
        }
        if (majorTitle == null) {
            menuList.addView(title, 0)
        } else {
            menuList.addView(title, 1)
        }
        return this
    }

    /**
     * 设置子项
     */
    fun setItem(text: String, textColor: Int = 0, itemClickListener: () -> Unit): IosBottomListWindow {
        val textView = TextView(activity)
        textView.apply {
            layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
                    LinearLayout.LayoutParams.WRAP_CONTENT).apply {
                setPadding(0, itemMargin, 0, itemMargin)
            }
            gravity = Gravity.CENTER
            setBackgroundResource(R.drawable.command_bg_click_xml)
            setTextSize(TypedValue.COMPLEX_UNIT_SP, 20f)
            if (textColor == 0) {
                setTextColor(Color.parseColor("#FF3B30"))
            } else {
                try {
                    setTextColor(textColor)
                } catch (e: Throwable) {
                    e.printStackTrace()
                }
            }
            setText(text)
            setOnClickListener {
                itemClickListener.invoke()
                dismiss()
            }
        }
        val lineView = View(activity).apply {
            layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, 1)
            setBackgroundColor(Color.parseColor("#dcdbdf"))
        }
        menuList.addView(lineView)
        menuList.addView(textView)
        return this
    }

    /**
     * 设置按钮
     */
    fun setCancelButton(text: String, textColor: Int = 0): IosBottomListWindow {
        val cancelView = TextView(activity).apply {
            layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
                    LinearLayout.LayoutParams.WRAP_CONTENT).apply {
                setMargins(commonMargin, 0, commonMargin, commonMargin)
            }
            setPadding(0, itemMargin, 0, itemMargin)
            background = resources.getDrawable(R.drawable.bottom_btn_click_xml, null)
            if (textColor == 0) {
                setTextColor(Color.parseColor("#FF3B30"))
            } else {
                try {
                    setTextColor(textColor)
                } catch (e: Throwable) {
                    e.printStackTrace()
                }
            }
            gravity = Gravity.CENTER
            setTextSize(TypedValue.COMPLEX_UNIT_SP, 20f)
            setText(text)
            typeface = Typeface.DEFAULT_BOLD
            setOnClickListener {
                dismiss()
            }
        }
        contentGroup.addView(cancelView)
        return this
    }

    /**
     * 初始化容器
     * 背景阴影容器
     */
    private fun initViewGroup() = FrameLayout(activity).apply {
        layoutParams = ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT)
        setOnClickListener {
            dismiss()
        }
    }

    /**
     * 初始化内容容器
     * 滑动动画载体
     */
    private fun initContentGroup() = LinearLayout(activity).apply {
        layoutParams = FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT,
                FrameLayout.LayoutParams.WRAP_CONTENT).apply {
            gravity = Gravity.BOTTOM
            bottomMargin = getBottomStatusHeight(activity)
            visibility = View.INVISIBLE
        }
        orientation = LinearLayout.VERTICAL
    }

    /**
     * 初始化菜单列表
     */
    private fun initMenuList() = LinearLayout(activity).apply {
        layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
                LinearLayout.LayoutParams.WRAP_CONTENT).apply {
            setMargins(commonMargin, 0, commonMargin, commonMargin)
        }
        gravity = Gravity.CENTER_HORIZONTAL
        orientation = LinearLayout.VERTICAL
        background = activity.resources.getDrawable(R.drawable.shape_bottom_list_menu, null)
    }

    private fun startAnimator(enterType: Boolean, listener: Animator.AnimatorListener? = null) {
        viewGroup.post {
            ValueAnimator().apply {
                if (enterType) {
                    setFloatValues(contentLayoutHeight.toFloat(), 0f)
                } else {
                    setFloatValues(0f, contentLayoutHeight.toFloat())
                }
                duration = 300
                interpolator = DecelerateInterpolator()
                addUpdateListener {
                    val value = it.animatedValue as Float
                    contentGroup.translationY = value
                    setShadow()
                }
                listener?.let {
                    addListener(it)
                }
                start()
            }
        }
    }

    private fun setShadow() {
        val ratio = contentGroup.translationY / contentLayoutHeight
        val shadow = (shadowMax * (1 - ratio)).toInt()
        if (shadow >= 16) {
            viewGroup.setBackgroundColor(Color.parseColor("#${shadow.toString(16)}000000"))
        }
    }

}

用到资源文件

shape_bottom_list_menu.xml
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <corners android:radius="15dp"/>
    <solid android:color="#f1f1f1"/>
</shape>

bottom_btn_click.xml
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
        android:color="@color/ColorRipe">
    <item android:drawable="@drawable/shape_bottom_list_button"/>
</ripple>

shape_bottom_list_button.xml
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <corners android:radius="15dp"/>
    <solid android:color="#ffffff"/>
</shape>

调用

            IosBottomListWindow(this)
                    .setTitle("上传头像")
                    .setMajorTitle("上传头像")
                    .setItem("从相册", resources.getColor(R.color.color_c10)) {
                        getPhotoFromAlbum()
                    }
                    .setItem("从相机") {
                        dispatchTakePictureIntent()
                    }
                    .setCancelButton("取消")
                    .show()

最后

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