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@davidsteppenbeck
Last active October 31, 2022 10:30
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A SwiftUI view modifier for simple preview providers.
import SwiftUI
enum PreviewProviderMode: CaseIterable {
/// Use for a light appearance preview.
case lightMode
/// Use for a dark appearance preview.
case darkMode
/// Use for a right-to-left layout preview.
case rightToLeft
/// Use for a preview with a large text size.
case largeText
/// Use for a redacted placeholder preview.
case redacted
}
fileprivate struct PreviewProviderModifier: ViewModifier {
/// The preview provider modes to display.
let modes: [PreviewProviderMode]
func body(content: Content) -> some View {
Group {
if modes.contains(.lightMode) {
content
.previewDisplayName("Light Mode")
.environment(\.colorScheme, .light)
}
if modes.contains(.darkMode) {
content
.previewDisplayName("Dark Mode")
.environment(\.colorScheme, .dark)
}
if modes.contains(.rightToLeft) {
content
.previewDisplayName("Right To Left")
.environment(\.layoutDirection, .rightToLeft)
}
if modes.contains(.largeText) {
content
.previewDisplayName("Large Text")
.environment(\.dynamicTypeSize, .accessibility5)
}
if modes.contains(.redacted) {
content
.previewDisplayName("Redacted")
.redacted(reason: .placeholder)
}
}
}
}
extension View {
/// Creates a group of views with various environment settings that are useful for previews.
///
/// - Parameters:
/// - modes: The preview provider modes to display, such as light mode, dark mode, right-to-left layout, and large text.
func makeForPreviewProvider(_ modes: [PreviewProviderMode] = PreviewProviderMode.allCases) -> some View {
modifier(PreviewProviderModifier(modes: modes))
}
/// Creates a group of views with various environment settings that are useful for previews.
///
/// - Parameters:
/// - mode: The preview provider mode to display, such as light mode, dark mode, right-to-left layout, or large text.
func makeForPreviewProvider(_ mode: PreviewProviderMode) -> some View {
modifier(PreviewProviderModifier(modes: [mode]))
}
/// Creates a group of views with various environment settings that are useful for previews.
///
/// - Parameters:
/// - modes: The preview provider modes to be excluded from being displayed. All other modes will be displayed.
func makeForPreviewProvider(excluding modes: [PreviewProviderMode]) -> some View {
let included = PreviewProviderMode.allCases.filter { modes.contains($0) == false }
return modifier(PreviewProviderModifier(modes: included))
}
/// Creates a group of views with various environment settings that are useful for previews.
///
/// - Parameters:
/// - mode: The preview provider mode to be excluded from being displayed. All other modes will be displayed.
func makeForPreviewProvider(excluding mode: PreviewProviderMode) -> some View {
makeForPreviewProvider(excluding: [mode])
}
}
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