How to Create Dialog Series Datepicker - Kotlin

MyDialogFragment.kt

class MyDialogFragment : DialogFragment() {

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        val dialog = activity?.let {
            // デフォルトの日付を用意
            val c = Calendar.getInstance()
            val year = c[Calendar.YEAR]
            val month = c[Calendar.MONTH]
            val day = c[Calendar.DAY_OF_MONTH]
            
            DatePickerDialog(it, null, year, month, day)
        }
        return dialog ?: throw IllegalStateException("アクティビティがNullです。")
    }
}