android - fatal error LifecycleOwners 必须在 registerForActivityResult 开始之前调用 register

Question

我有一个简单的空 Activity 来检查是否需要请求权限。当registerForActivityResult被调用，它会崩溃并出现错误 java.lang.IllegalStateException: LifecycleOwner com.example.app.PermsRequester@41a30da is attempting to register while current state is RESUMED. LifecycleOwners must call register before they are STARTED.根据我的研究，我认为我需要检查 savedInstanceState是 null如果是这样，创建一个新的fragment ?我不确定这是否是正确的解决方案或如何实现。下面是代码:

class PermsRequester : AppCompatActivity() {
    requestPerms = false

    override fun onCreate(savedInstanceState: Bundle?) {
        setTheme(R.style.AppTheme)
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_perms_requester)

        findViewById<Button>(R.id.acceptButton).setOnClickListener { accepted() }
    }

    private fun accepted() {
        //There is code here to check if rationale dialog needs to be displayed
        //There is code here to build a mutable list of permissions that need to be requested and sets requestPerms = true

        if(requestPerms)
            requestPermissions()
    }

    private fun requestPermissions() {
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            //app crashes on the following line
            val requestMultiplePermissions = registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) {
                 permissions -> permissions.entries.forEach {
                     //Handles permission result
                 }
            }
        }
    }
}

Answer 1

您需要 registerForActivityResult之前 onStart的 Activity 。

private lateinit var requestMultiplePermissionsLauncher: 
    ActivityResultLauncher<Array<String>>

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    requestMultiplePermissionsLauncher =
        registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) { permissions ->
            permissions.entries.forEach {
                //Handles permission result
            }
        }
}

private fun accepted() {
    if(requestPerms) {
        val permissions = arrayOf(Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.CAMERA)
        requestMultiplePermissionsLauncher.launch(permissions)
    }
}