Recently I am learning how to use Jetpack and Kotlin. Compared with onActivityResult, Androidx-activity 1.2.0-Alpha02 and Fragment 1.3.0-Alpha02 add API ActivityResultContract

Environment configuration

To use ActivityResultContract, we need to add dependencies to the Gradle file, and here I’m using version Alpha03

implementation "Androidx. Activity: activity - KTX: 1.2.0 - alpha03"
implementation 'androidx. Fragments: fragments - KTX: 1.3.0 - alpha03'
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Method of use

ActivityResultContract and fragments can be registerForActivityResult () function creates the launcher, Then through a call to the launcher. The launch (intent) to use Because of version or other force majeure, I found in the use process registerForActivityResult () do not use, access to information found that RegisterForActivityResult () is prepareCall rename (), so can only temporarily use prepareCall ()

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Set up the launcher

private val launcher = prepareCall(ActivityResultContracts.GetContent()) { uri ->
       Toast.makeText(context,"uri:$uri",Toast.LENGTH_SHORT).show()
   }
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The launcher calls to launch

launcher.launch("image/*")
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RequestPermission

The premise

To obtain permissions dynamically, fill in the corresponding statement in the AndroidManifest, for example, WRITE_EXTERNAL_STORAGE

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
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Set up the launcher

    val requestPermissionLauncher =
        prepareCall(
            ActivityResultContracts.RequestPermission()
        ) { isGranted: Boolean ->
            if (isGranted) {
                Toast.makeText(context, "result: granted", Toast.LENGTH_LONG).show()
            } else {
                Toast.makeText(context, "result:fail", Toast.LENGTH_LONG).show()
            }
        }
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The launcher calls to launch

requestPermissionLauncher.launch(WRITE_EXTERNAL_STORAGE)
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conclusion

I spent the afternoon looking at the permissions for Jetpack. Write an article about the holes you’ve stomped on. It’s true that using Jetpack makes your code a lot cleaner