The project's goal is to stay close to the original API as possible.
Currently, this project is in early development.
Background
Apple introduced SwiftUI at WWDC 19. Since then, developing applications with graphical user interfaces became more comfortable to read, write, and maintain. Unfortunately, the principle "Learn once, apply anywhere" works on Apple platforms, only.
Swift runs on Apple platforms, the web, Linux, Windows, and even on embedded devices.
Wouldn't it be great if you could write GUI based applications with SwiftUI on platforms that run Swift?
SwiftUI on your platform
OpenSwiftUI provides the API — other projects can implement the actual rendering of UI elements for different platforms like Linux, Windows, Embedded, and many more.
SwiftUIEmbedded is one of the first projects that make use of OpenSwiftUI (Demo).
Contributing
Over time and collective guesswork, it should be possible to re-create the complete SwiftUI API from Apple.
Check the Status overview to see what's missing or needs to be completed.
A good starting point is to get familiar with the SwiftUI interface, focus on certain functionality, and try to re-implement it.
A helpful tool is to use reflection (Mirror(reflecting: …)) to peek into SwiftUI types and instances. This reveals the internal structure of instances (properties, types, names and inheritance).
Once you implemented a missing piece, please feel free to contribute a pull request.
Please note:
Private methods and properties of SwiftUI should be prefixed by an _ (underscore) and marked as public in OpenSwiftUI.
Doing this is necessary because the frontend might need access.
Xcode 11.2 or higher is required.
Status
Views and Controls
Essentials
Status
Name
Notes
✅
protocol View
Text
Status
Name
Notes
✅
struct Text
❌
struct TextField
❌
struct SecureField
✅
struct Font
Images
Status
Name
Notes
⚠️
struct Image
CGImage not supported
Buttons
Status
Name
Notes
✅
struct Button
❌
struct NavigationLink
❌
struct MenuButton
❌
struct EditButton
❌
struct PasteButton
Value Selectors
Status
Name
Notes
❌
struct Toggle
⚠️
struct Picker
❌
struct DatePicker
❌
struct Slider
⚠️
struct Stepper
Supporting Types
Status
Name
Notes
✅
struct ViewBuilder
✅
protocol ViewModifier
View Layout and Presentation
Stacks
Status
Name
Notes
✅
struct HStack
✅
struct VStack
✅
struct ZStack
Lists and Scroll Views
Status
Name
Notes
❌
struct List
❌
protocol DynamicViewContent
✅
protocol Identifiable
Provided by Swift.
✅
struct ForEach
❌
struct ScrollView
⚠️
enum Axis
Container Views
Status
Name
Notes
❌
struct Form
⚠️
struct Group
❌
struct GroupBox
❌
struct Section
Spacer and Dividers
Status
Name
Notes
✅
struct Spacer
✅
struct Divider
Architectural Views
Status
Name
Notes
❌
struct NavigationView
❌
struct TabView
❌
struct HSplitView
❌
struct VSplitView
Presentations
Status
Name
Notes
❌
struct Alert
❌
struct ActionSheet
Conditionally Visible Items
Status
Name
Notes
✅
struct EmptyView
❌
struct EquatableView
Infrequently Used Views
Status
Name
Notes
⚠️
struct AnyView
init?(_fromValue value: Any) missing.
✅
struct TupleView
Drawing and Animation
Essentials
Status
Name
Notes
⚠️
protocol Shape
Animation
Status
Name
Notes
❌
struct Animation
❌
protocol Animatable
❌
protocol AnimatableModifier
❌
func withAnimation<Result>(Animation?, () -> Result) -> Result
❌
struct AnimationPair
❌
struct EmptyAnimationData
❌
struct AnyTransition
Shapes
Status
Name
Notes
⚠️
struct Rectangle
✅
enum Edge
❌
struct RoundedRectangle
⚠️
struct Circle
❌
struct Ellipse
❌
struct Capsule
❌
struct Path
Transformed Shapes
Status
Name
Notes
❌
protocol InsettableShape
❌
struct ScaledShape
❌
struct RotatedShape
❌
struct OffsetShape
❌
struct TransformedShape
Paints, Styles, and Gradients
Status
Name
Notes
✅
struct Color
❌
struct ImagePaint
❌
struct Gradient
❌
struct LinearGradient
❌
struct AngularGradient
❌
struct RadialGradient
❌
struct ForegroundStyle
❌
struct FillStyle
❌
protocol ShapeStyle
❌
enum RoundedCornerStyle
❌
struct SelectionShapeStyle
❌
struct SeparatorShapeStyle
❌
struct StrokeStyle
Geometry
Status
Name
Notes
❌
struct GeometryProxy
❌
struct GeometryReader
❌
protocol GeometryEffect
❌
struct Angle
❌
struct Anchor
❌
struct UnitPoint
❌
enum CoordinateSpace
❌
struct ProjectionTransform
❌
protocol VectorArithmetic
State and Data Flow
Bindings
Status
Name
Notes
⚠️
struct Binding
Data-Dependent Views
Status
Name
Notes
✅
struct State
❌
struct ObservedObject
❌
struct EnvironmentObject
❌
struct FetchRequest
❌
struct FetchedResults
⚠️
protocol DynamicProperty
func update() missing.
Environment Values
Status
Name
Notes
✅
struct Environment
✅
struct EnvironmentValues
Preferences
Status
Name
Notes
❌
protocol PreferenceKey
❌
struct LocalizedStringKey
Transactions
Status
Name
Notes
❌
struct Transaction
Gestures
Basic Gestures
Status
Name
Notes
❌
struct TapGesture
❌
struct LongPressGesture
❌
struct DragGesture
❌
struct MagnificationGesture
❌
struct RotationGesture
Combined Gestures
Status
Name
Notes
❌
struct SequenceGesture
❌
struct SimultaneousGesture
❌
struct ExclusiveGesture
Custom Gesture
Status
Name
Notes
❌
protocol Gesture
❌
struct AnyGesture
Dynamic View Properties
Status
Name
Notes
❌
struct GestureState
❌
struct GestureStateGesture
Gesture Support
Status
Name
Notes
❌
struct GestureMask
❌
struct EventModifiers
Legend
Symbol
Description
✅
Done
❌
Open
⚠️
Incomplete
Resources
SwiftUI Interface
Compared to what you can see in Xcode, this gist shows you more than just the public interfaces.
It shows private properties, and the body of @inlinable marked properties, functions, and initializers.
SwiftWebUI is an implementation of SwiftUI for the web by Helge Heß.
This project's goal is focused exclusively on the web.
It deviates a little bit from SwiftUI by taking some shortcuts here and there -- but looks quite complete in functionality and is great for inspiration.
SwiftUI symbols
This command prints the symbol table of SwiftUI via the llvm-mn utility.
nm -gUj /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/SwiftUI.framework/SwiftUI | swift-demangle | sed 's/SwiftUI.//g'| sed 's/Swift.//g'
I want to give special thanks to Helge Heß. He created SwiftWebUI, contributed many suggestions to OpenSwiftUI, and helped with insights of his findings.
