Previews in Xcode

Overview

When you create a custom View with SwiftUI, Xcode can display a preview of the view’s content that stays up-to-date as you make changes to the view’s code. You use one of the preview macros — like Preview(_:body:) — to tell Xcode what to display. Xcode shows the preview in a canvas beside your code.

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Different preview macros enable different kinds of configuration. For example, you can add traits that affect the preview’s appearance using the Preview(_:traits:_:body:) macro or add custom viewpoints for the preview using the Preview(_:traits:body:cameras:) macro. You can also check how your view behaves inside a specific scene type. For example, in visionOS you can use the Preview(_:immersionStyle:traits:body:) macro to preview your view inside an ImmersiveSpace.

You typically rely on preview macros to create previews in your code. However, if you can’t get the behavior you need using a preview macro, you can use the PreviewProvider protocol and its associated supporting types to define and configure a preview.

Topics

Essentials

• Previewing your app’s interface in Xcode

Creating a preview

• Preview(_:body:)
• Preview(_:traits:_:body:)
• Preview(_:traits:body:cameras:)

Creating a preview in the context of a scene

• Preview(_:immersionStyle:traits:body:)
• Preview(_:immersionStyle:traits:body:cameras:)
• Preview(_:windowStyle:traits:body:)
• Preview(_:windowStyle:traits:body:cameras:)

Defining a preview

• Previewable()
• PreviewProvider
• PreviewPlatform
• previewDisplayName(_:)
• PreviewModifier
• PreviewModifierContent

Customizing a preview

• previewDevice(_:)
• PreviewDevice
• previewLayout(_:)
• previewInterfaceOrientation(_:)
• InterfaceOrientation

Setting a context

• previewContext(_:)
• PreviewContext
• PreviewContextKey

Building in debug mode

• DebugReplaceableView

See Also

Tool support

• Xcode library customization
• Performance analysis