Notifications are a way to inform users of your app about events, even if the applications has no focus, is minimized, or is only running in the background.
Is this the right control?
Use notifications to inform the user of events that are of interest, even if your app is not in foreground, but don't spam the user with notifications.
- Completion of long running tasks that the user has started manually
- Incoming communication from other users
- Hardware related events like low battery, lost network connection, running out of disk space
Don't use a notification for:
- Operations that don't require user interaction, such as background processes, syncing, or updates
- Advertising, rating or feedback requests, or other annoyances
- If an unexpected or potentially dangerous condition has been
reached and the user must make a decision. Use an
- Don't send notifications if an user has never opened your application
Notifications are provided by the system to the user, and foremost the user settings for notification govern the behavior and appearance of notifications. But there are several options to influence and enrich the behavior of your notifications.
Making a notification persistent will prevent it from closing after a timeout. Your app must revoke the persistent notification, if the reason for the notification no longer applies, like a power adapter was plugged after a "Laptop battery is almost empty" notification. Use this if the notification requires user interaction, e.g. a device is asking for pairing confirmation.
It is recommended that a notification carries an urgency hint:
- 0 -- Low, "Matt is now online", "You just plugged in your AC adapter"
- 1 -- Normal, "You have new mail"
- 2 -- Critical, "Laptop battery is almost empty"
You can add up to three action buttons to the notification to enable the user to react to the event without having to go to the app itself.
You can specify a URL to an image associated with the notification. The image will be displayed as a preview in the notification.
KNotification *notification = new KNotification("contactOnline", widget); notification->setText(i18n("The contact %1 has gone online", contact->name()); notification->setPixmap(contact->pixmap()); notification->setActions(QStringList(i18n("Open chat"))); connect(notification, SIGNAL(activated(unsigned int)), contact , SLOT(slotOpenChat())); notification->sendEvent();