DialogFragment从单词可以看到是Dialog与Fragment组合而成。本质上DialogFragment其实是一个Fragment，内部持有一个Dialog，拥有fragment的生命周期，DialogFragment有两个比较重要的方法onCreateDialog和onCreateView

onCreateDialog和onCreateView只需要实现一个就可以了

如果两个都写并且onCreateDialog返回了一个Dialog子类实例对象，则onCreateView返回的视图无效

class MyAlertDialogFragment : DialogFragment() {

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        val builder = AlertDialog.Builder(requireActivity())
            .setTitle("Alert Dialog Title")
            .setMessage("This is an example of an AlertDialog.")
            .setPositiveButton("OK") { dialog, which ->
                // 响应正面按钮点击事件
            }
            .setNegativeButton("Cancel") { dialog, which ->
                dialog.dismiss()
            }

        return builder.create() // 返回 AlertDialog
    }
}

// 显示 DialogFragment
val dialogFragment = MyAlertDialogFragment()
dialogFragment.show(supportFragmentManager, "myAlertDialog")

1、简单UI：比如如返回一个系统的AlertDialog只需要在onCreateDialog返回一个AlertDialog即可
2、自定义复杂UI，实现onCreateView返回自定义视图

加载自定义视图的方式

1、使用普通

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    return inflater.inflate(R.layout.my_dialog,container,false)
}

2、使用View Binding

class MyDialogFragment : DialogFragment() {

    private var _binding: DialogFragmentLayoutBinding? = null
    private val binding get() = _binding!!

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        _binding = DialogFragmentLayoutBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        // 设置按钮点击事件
        binding.button.setOnClickListener {
            dismiss() // 关闭对话框
        }
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null // 清理绑定
    }
}

3、使用Data Binding

class MyDialogFragment : DialogFragment() {

    private var _binding: DialogFragmentLayoutBinding? = null
    private val binding get() = _binding!!

    private lateinit var viewModel: MyViewModel

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        _binding = DataBindingUtil.inflate(inflater, R.layout.dialog_fragment_layout, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        viewModel = ViewModelProvider(this).get(MyViewModel::class.java)
        binding.viewModel = viewModel // 绑定 ViewModel
        binding.lifecycleOwner = viewLifecycleOwner // 设置生命周期所有者
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null // 清理绑定
    }
}