應用程序權限

當今設備和 OS (操作係統) 的許多特徵可能對隱私、安全性、及性能有顯著影響，若濫用。因此，要求用戶明確同意的平颱越來越普遍，在訪問這些特徵之前。

Qt 權限 API 允許應用程序以跨平颱方式，校驗 (或請求) 這些特性的權限。

用法

A feature that commonly requires user consent is access to the microphone of the device. An application for recording voice memos would perhaps look something like this initially:

void VoiceMemoWidget::onRecordingInitiated()
{
    m_microphone->startRecording();
}

To ensure this application works well on platforms that require user consent for microphone access we would extend it like this:

void VoiceMemoWidget::onRecordingInitiated()
{
    QMicrophonePermission microphonePermission;
    switch (qApp->checkPermission(microphonePermission)) {
    case Qt::PermissionStatus::Undetermined:
        qApp->requestPermission(microphonePermission, this,
                    &VoiceMemoWidget::onRecordingInitiated);
        return;
    case Qt::PermissionStatus::Denied:
        m_permissionInstructionsDialog->show();
        return;
    case Qt::PermissionStatus::Granted:
        m_microphone->startRecording();
    }
}

We first check if we already know the status of the microphone permission. If we don't we initiate a permission request to determine the current status, which will potentially ask the user for consent. We connect the result of the request to the slot we're already in, so that we get another chance at evaluating the permission status.

Once the permission status is known, either because we had been granted or denied permission at an earlier time, or after getting the result back from the request we just initiated, we redirect the user to a dialog explaining why we can not record voice memos at this time (if the permission was denied), or proceed to using the microphone (if permission was granted).

注意： On macOS and iOS permissions can currently only be requested for GUI applications.

聲明權限

Some platforms require that the permissions you request are declared up front at build time.

Apple 平颱

請求的每個權限都必須附有所謂的 用法描述 字符串在應用程序的 Info.plist 文件，描述應用程序為什麼需要訪問給定權限。例如：

<key>NSMicrophoneUsageDescription</key>
<string>The microphone is used to record voice memos.</string>

每種權限類型的相關用法描述鍵，在文檔編製中有描述。

要確保相關權限後端包括在應用程序中，請把構建係統指嚮自定義 Info.plist .

Android

請求的每個權限都必須附有 uses-permission 條目在應用程序的 AndroidManifest.xml 文件。例如：

<manifest ...>
    <uses-permission android:name="android.permission.RECORD_AUDIO"/>
</manifest>

要確保相關權限後端包括在應用程序中，請把構建係統指嚮自定義 AndroidManifest.xml 或使用 qt_add_android_permission()。

每種權限類型的相關權限名稱，在文檔編製中有描述。

可用權限

下列權限類型可用：

QBluetoothPermission	訪問藍牙外圍設備
QCalendarPermission	訪問用戶的日曆
QCameraPermission	訪問攝像頭為取得圖片 (或視頻)
QContactsPermission	訪問用戶的聯係人
QLocationPermission	訪問用戶的位置
QMicrophonePermission	為監視訪問麥剋風 (或錄製聲音)

注意： The available permission types cover core functionality of Qt modules like Qt Multimedia and Qt Positioning, but do not encompass all platform-specific permissions. Custom permission types are not currently supported.

最佳實踐

To ensure the best possible user experience for the end user we recommend adopting the following best practices for managing application permissions:

Request the minimal set of permissions needed. For example, if you only need access to the microphone, do not request camera permission just in case. Use the properties of individual permission types to limit the permission scope even further, for example QContactsPermission::setAccessMode () to request read only access.
Request permissions in response to specific actions by the user. For example, defer requesting microphone permission until the user presses the button to record audio. Associating the permission request to a specific action gives the user a clearer context of why the permission is needed. Do not request all needed permission on startup.
Present extra context and explanation if needed. Sometimes the action by the user is not enough context. Consider presenting an explanation-dialog after the user has initiated the action, but before requesting the permission, so the user is aware of what's about to happen when the system permission dialog subsequently pops up.
Be transparent and explicit about why permissions are needed. In explanation dialogs and usage descriptions, be transparent about why the particular permission is needed for your application to provide a specific feature, so users can make informed decisions.
Account for denied permissions. The permissions you request may be denied for various reasons. You should always account for this situation, by gracefully degrading the experience of your application, and presenting clear explanations the user about the situation.
Never request permissions from a library. The request of permissions should be done as close as possible to the user, where the information needed to make good decisions on the points above is available. Libraries can check permissions, to ensure they have the prerequisites for doing their work, but if the permission is undetermined or denied this should be reflected through the library's API, so that the application in turn can request the necessary permissions.

另請參閱 信息特性列錶文件 and Qt Creator：編輯清單文件 .

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