SkipKit

This Skip Lite module enhances the SkipUI package with commonly-used features, such as a permission checker and a picker for photos and other media.

PermissionManager

The PermissionManager provides the ability to request device permissions.

For example:

import SkipKit
import SkipDevice

let locationProvider = LocationProvider()

if await PermissionManager.requestPermission(.ACCESS_FINE_LOCATION) == true {
    let location = try await locationProvider.fetchCurrentLocation()
}

In addition to symbolic constants, there are also functions for requesting specific permissions with various parameters:

static func queryLocationPermission(precise: Bool, always: Bool) -> PermissionAuthorization
static func requestLocationPermission(precise: Bool, always: Bool) async -> PermissionAuthorization

static func queryPostNotificationPermission() async -> PermissionAuthorization
static func requestPostNotificationPermission(alert: Bool = true, sound: Bool = true, badge: Bool = true) async throws -> PermissionAuthorization

static func queryCameraPermission() -> PermissionAuthorization
static func requestCameraPermission() async -> PermissionAuthorization

static func queryRecordAudioPermission() -> PermissionAuthorization
static func requestRecordAudioPermission() async -> PermissionAuthorization

static func queryContactsPermission(readWrite: Bool) -> PermissionAuthorization
static func requestContactsPermission(readWrite: Bool) async throws -> PermissionAuthorization

static func queryCalendarPermission(readWrite: Bool) -> PermissionAuthorization
static func requestCalendarPermission(readWrite: Bool) async throws -> PermissionAuthorization

static func queryReminderPermission(readWrite: Bool) -> PermissionAuthorization
static func requestReminderPermission(readWrite: Bool) async throws -> PermissionAuthorization

static func queryPhotoLibraryPermission(readWrite: Bool) -> PermissionAuthorization
static func requestPhotoLibraryPermission(readWrite: Bool) async -> PermissionAuthorization

To request an arbitrary Android permission for which there may be no iOS equivalent, you can pass the string literal. For a list of common permission literals, see https://developer.android.com/reference/android/Manifest.permission.

For example, to request the SMS sending permission:

let granted = await PermissionManager.requestPermission("android.permission.SEND_SMS")

Camera and Media selection

The View.withMediaPicker(type:isPresented:selectedImageURL:) extension function can be used to enable the acquisition of an image from either the system camera or the user's media library.

On iOS, this camera selector will be presented in a fullScreenCover view, whereas the media library browser will be presented in a sheet. In both cases, a standad UIImagePickerController will be used to acquire the media.

On Android, the camera and library browser will be activated through an Intent after querying for the necessary permissions.

Following is an example of implementing a media selection button that will bring up the system user interface.

import SkipKit

/// A button that enables the selection of media from the library or the taking of a photo.
///
/// The selected/captured image will be communicated through the `selectedImageURL` binding,
/// which can be observed with `onChange` to perform an action when the media URL is acquired.
struct MediaButton : View {
    let type: MediaPickerType // either .camera or .library
    @Binding var selectedImageURL: URL?
    @State private var showPicker = false

    var body: some View {
        Button(type == .camera ? "Take Photo" : "Select Media") {
            showPicker = true // activate the media picker
        }
        .withMediaPicker(type: .camera, isPresented: $showPicker, selectedImageURL: $selectedImageURL)
    }
}

Camera and Media Permissions

In order to access the device's photos or media library, you will need to declare the permissions in the app's metadata.

On iOS this can be done by editing the Darwin/AppName.xcconfig file and adding the lines:

INFOPLIST_KEY_NSCameraUsageDescription = "This app needs to access the camera";
INFOPLIST_KEY_NSPhotoLibraryUsageDescription = "This app needs to access the photo library.";

On Android, the app/src/main/AndroidManifest.xml file will need to be edited to include camera permissions as well as a FileProvider implementation so the camera can share a Uri with the app. For example:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools">
    <!-- features and permissions needed in order to use the camera and read/write photos -->
    <uses-feature
        android:name="android.hardware.camera"
        android:required="false" />
    <uses-feature
        android:name="android.hardware.camera.autofocus"
        android:required="false" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <application
        android:label="${PRODUCT_NAME}"
        android:name=".AndroidAppMain"
        android:supportsRtl="true"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:configChanges="orientation|screenSize|screenLayout|keyboardHidden|mnc|colorMode|density|fontScale|fontWeightAdjustment|keyboard|layoutDirection|locale|mcc|navigation|smallestScreenSize|touchscreen|uiMode"
            android:theme="@style/Theme.AppCompat.DayNight.NoActionBar"
            android:windowSoftInputMode="adjustResize">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <!-- needed in order for the camera to be able to share the photo with the app -->
        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="${applicationId}.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths" />
        </provider>
    </application>
</manifest>

In addition to editing the manifest, you must also manually create the xml/file_paths reference from the manifest's provider. This is done by creating the folder Android/app/src/main/res/xml in your Skip project and adding a file file_paths.xml with the following contents:

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path name="my_images" path="." />
    <cache-path name="*" path="." />
</paths>

For an example of a properly configured project, see the Photo Chat sample application.

Document Picker

The View.withDocumentPicker(isPresented: Binding<Bool>, allowedContentTypes: [UTType], selectedDocumentURL: Binding<URL?>, selectedFilename: Binding<String?>, selectedFileMimeType: Binding<String?>) extension function can be used to select a document of the specified UTType from the device to use in the App.

On iOS it will use an instance of FileImporter to display the system file picker, essentially allowing to select a file from the Files application, while on Android it relies on the the system document picker via the Activity result for the ACTION_OPEN_DOCUMENT. Once the user selects a file it will receive an uri, that need to be parsed to be used outside the scope of the caller. For doing so it will copy the file inside the App cache folder and expose the cached url instead of the original picked file url.

For example:

Button("Pick Document") {
    presentPreview = true
}
.buttonStyle(.borderedProminent)
.withDocumentPicker(isPresented: $presentPreview, allowedContentTypes: [.image, .pdf], selectedDocumentURL: $selectedDocument, selectedFilename: $filename, selectedFileMimeType: $mimeType)

Document Preview

The View.withDocumentPreview(isPresented: Binding<Bool>, documentURL: URL?, filename: String?, type: String?) extension function can be used to preview a document available to the app (either selected with the provided Document Picker or downloaded locally by the App). On iOS it will use an instance of QLPreviewController to display the file at the provided url while on Android it will open an Intent chooser for selecting the appropriate app for the provided file mime type. On iOS there's no need to provide a filename or a mime type, but sometimes on Android is necessary (for example when selecting a document using the document picker). On Android if no mime type is supplied it will try to guess it by the file url. If no mime type can be found the application chooser will be empty. A file provider (like the one used for using the MediaPicker) is necessary for the Intent to correctly pass reading permission to the receiving app. As long as your Skip already implements the FileProvider and the file_paths.xml as described in the Camera and Media Permission section there's nothing else needed, otherwise you need to follow the instructions in the mentioned section.

Building

This project is a free Swift Package Manager module that uses the Skip plugin to transpile Swift into Kotlin.

Building the module requires that Skip be installed using Homebrew with brew install skiptools/skip/skip. This will also install the necessary build prerequisites: Kotlin, Gradle, and the Android build tools.

Testing

The module can be tested using the standard swift test command or by running the test target for the macOS destination in Xcode, which will run the Swift tests as well as the transpiled Kotlin JUnit tests in the Robolectric Android simulation environment.

Parity testing can be performed with skip test, which will output a table of the test results for both platforms.

Contributing

We welcome contributions to this package in the form of enhancements and bug fixes.

The general flow for contributing to this and any other Skip package is:

1. Fork this repository and enable actions from the "Actions" tab
2. Check out your fork locally
3. When developing alongside a Skip app, add the package to a shared workspace to see your changes incorporated in the app
4. Push your changes to your fork and ensure the CI checks all pass in the Actions tab
5. Add your name to the Skip Contributor Agreement
6. Open a Pull Request from your fork with a description of your changes

License

This software is licensed under the GNU Lesser General Public License v3.0, with the following linking exception to clarify that distribution to restricted environments (e.g., app stores) is permitted:

This software is licensed under the LGPL3, included below. As a special exception to the GNU Lesser General Public License version 3 ("LGPL3"), the copyright holders of this Library give you permission to convey to a third party a Combined Work that links statically or dynamically to this Library without providing any Minimal Corresponding Source or Minimal Application Code as set out in 4d or providing the installation information set out in section 4e, provided that you comply with the other provisions of LGPL3 and provided that you meet, for the Application the terms and conditions of the license(s) which apply to the Application. Except as stated in this special exception, the provisions of LGPL3 will continue to comply in full to this Library. If you modify this Library, you may apply this exception to your version of this Library, but you are not obliged to do so. If you do not wish to do so, delete this exception statement from your version. This exception does not (and cannot) modify any license terms which apply to the Application, with which you must still comply.