Feedback helps people know what an app is doing, discover what they can do next, and understand the results of actions.
Unobtrusively integrate status and other types of feedback into your interface. Ideally, users can get important information without taking action or being interrupted. Mail, for example, subtly displays status information in the toolbar while navigating through mailboxes of messages. This information doesn’t compete with the primary content onscreen, but can be checked at any time with a quick glance.
Avoid unnecessary alerts. An alert is a powerful feedback mechanism, but should be used only to deliver important—and ideally actionable—information. If people see too many alerts that don’t contain essential information, they quickly learn to ignore future alerts. For additional guidance, see Alerts.
On supported devices, haptics provide a way to physically engage users with tactile feedback that gets attention and reinforces actions. Some system-provided interface elements, such as pickers, switches, and sliders, automatically provide haptic feedback as users interact with them. Your app can also ask the system to generate different types of haptic feedback. iOS manages the strength and behavior of this feedback.
Use haptics judiciously. Overuse can cause confusion and diminish the significance of feedback.
In general, provide haptic feedback in response to user-initiated actions. It’s easy for people to correlate haptics with actions they initiated. Arbitrary feedback can feel disconnected and be misinterpreted.
Don’t redefine feedback types. To ensure a consistent experience, use feedback types as intended. Don’t, for example, use "impact" feedback to notify the user that a task has succeeded. Instead, use the "success" variation of "notification" feedback.
Fine tune your visual experience for haptics. Provide visual and haptic feedback together to create a deeper connection between actions and results. Make sure animations are sharp and precise, to visually match what the user feels.
Don’t rely on a single mode of communication. Not all devices support the full range of haptic feedback, and people can disable the feature entirely in Settings if they choose. In addition, haptic feedback occurs only when the device is active and your app is frontmost. Supplement haptics with visual and audible cues to ensure that important information isn’t missed.
Use haptics when visual feedback may be occluded. Some interactions, such as dragging an object to a location onscreen, are hidden by the user’s finger. Consider generating feedback that lets the user know when they’ve reached a particular location or value.
Prepare the system before initiating feedback. Because there may be some latency involved when providing haptic feedback, it’s best to get the system ready shortly before requesting the feedback. Otherwise, the haptics might come too late and feel disconnected from the user's actions or what they’re seeing on the screen.
Synchronize haptics with accompanying sound. Haptics don’t automatically synchronize with sounds. If you want an accompanying sound, you’re responsible for synchronizing it.
For developer guidance, see Animation and Haptics.