Work with windows in SwiftUI

Key takeaways

• 🪟 Windows are containers for app contents, allowing users to see different pieces of data at the same time, or have multiple instances of the same interface.

• ✨ SwiftUI provides a few environment actions to work with windows.

• ↔️ You can set a default position and size for windows, but users can move or resize windows (within your frame constraints).

Presenters

Andrew Sawyer, SwiftUI Engineer

Overview

• Windows are a container for the contents of your app.

• Users can reposition, resize, or close windows using consistent controls.

Fundamentals

• Windows allow users to use different parts of your app at the same time, or have multiple instances of the same interface.

• Windows are defined using WindowGroup in SwiftUI. WindowGroups may have multiple styles, such as .windowStyle(.volumetric) for visionOS.

• WindowGroups should have an id, which is used to open an instance of that window.

• Environment actions, which are available anywhere in the SwiftUI view hierarchy, can be used to work with windows.

  • openWindow is used to open windows by ID.

  • dismissWindow is used to close windows.

  • pushWindow can be used to open a new window and hide the originating window. When you close the new window, the original window will reappear.

• The title bar and close button are always visible by default, but you can use the .persistentSystemOverlays(.hidden) modifier to hide them.

Placement

• Default window position varies by platform, but it can be customized with the defaultWindowPlacement modifier.

• You can return different placements depending on the platform by using the #if os(…) directive.

• defaultWindowPlacement takes a block that receives a context parameter, which includes metrics for the defaultDisplay on macOS.

Sizing

• Window sizing, by default, is automatically determined by the system.

• You can set other sizing as part of the WindowPlacement return value of defaultWindowPlacement.

• WindowLayoutRoot, one of the parameters to the defaultWindowPlacement block, includes a sizeThatFits(…) method that allows you to get a size for some given window content.

• You can also use the defaultSize modifier on the WindowGroup directly.

• Default sizes are ignored if there are other size constraints, like a size provided by the window placement API or when windows are restored.

• A pushed window, by default, has the same size as its originating window.

• Use the windowResizability(.contentSize) modifier to constrain window resizability to the allowable range of sizes for the window’s content.

  • If the window content has a fixed size, rather than a range of min and max sizes, then the window will not be resizable.