Human Interface Guidelines: Modality

Modality is a design technique that presents content in a temporary mode that’s separate from the user's previous current context and requires an explicit action to exit. Presenting content modally can:

• Help people focus on a self-contained task or set of closely related options
• Ensure that people receive and, if necessary, act on critical information

Alert

Modal View

iOS provides Alerts, Activity Views (or Share sheets), and Action Sheets that you use in specific situations in your app. To present custom modal content in your app, iOS 13 and later supports the following presentation styles.

Sheet

The sheet presentation style appears as a card that partially covers the underlying content and dims all uncovered areas to prevent interaction with them. The top edge of the parent view or a previous card is visible behind the current card to help people remember the task they suspended when they opened the card. People dismiss a card by:

• Swiping down from the top of the screen 
• Swiping down from anywhere on the screen when card content is scrolled to the top
• Tapping a button

Use a sheet for nonimmersive modal content that doesn’t enable a complex task.

Fullscreen

The fullscreen presentation style covers the entire screen. The previous view is completely covered, minimizing visual distraction. People dismiss a full-screen modal view by tapping a button.

Use a full-screen modal view for immersive content — such as videos, photos, or camera views — or a complex task that benefits from a full-screen presentation, such as marking up a document or editing a photo.

NOTEIf you use the current context modal view style to display modal content within a split view pane, popover, or other view that isn’t fullscreen, you should switch to using a sheet when presenting modal content in a compact environment.

 

developer.apple.com/design/human-interface-guidelines/ios/app-architecture/modality/

Modality - App Architecture - iOS - Human Interface Guidelines - Apple Developer