August 27, 2025

SwiftJsonUI 7.1.1 introduces binding properties for custom components, enabling two-way data binding between parent and child components in SwiftUI mode.

Custom components can now have binding properties that allow two-way data flow:

• Prefix attribute names with @ when generating components to create binding properties
• Use @{propertyName} syntax in JSON to bind to ViewModel data
• Full support in both Static and Dynamic modes
• Proper SwiftUI.Binding generation for type-safe bindings

1. Generate a Component with Binding Properties:

sjui g converter UserProfile --attributes "@user:User,@isEditing:Bool,showDetails:Bool"

2. Generated Swift Component:

struct UserProfile<Content: View>: View {
    @SwiftUI.Binding var user: User        // Binding property
    @SwiftUI.Binding var isEditing: Bool   // Binding property
    let showDetails: Bool                  // Regular property
    let content: Content?
    
    init(
        user: SwiftUI.Binding<User>,
        isEditing: SwiftUI.Binding<Bool>,
        showDetails: Bool,
        @ViewBuilder content: () -> Content = { EmptyView() }
    ) {
        self._user = user
        self._isEditing = isEditing
        self.showDetails = showDetails
        self.content = content()
    }
    
    var body: some View {
        VStack {
            // Your custom UI here
            // Can read and write to binding properties
            TextField("Name", text: $user.name)
            Toggle("Edit Mode", isOn: $isEditing)
            if showDetails {
                Text("Details section")
            }
        }
    }
}

3. Use in JSON:

{
  "type": "UserProfile",
  "user": "@{currentUser}",      // Binds to $viewModel.data.currentUser
  "isEditing": "@{editMode}",     // Binds to $viewModel.data.editMode  
  "showDetails": true              // Static value (not a binding)
}

4. Define Data in Parent View:

{
  "data": [
    {
      "name": "currentUser",
      "class": "User",
      "defaultValue": {
        "name": "John Doe",
        "email": "[email protected]"
      }
    },
    {
      "name": "editMode",
      "class": "Bool",
      "defaultValue": false
    }
  ],
  "child": [
    {
      "type": "UserProfile",
      "user": "@{currentUser}",
      "isEditing": "@{editMode}",
      "showDetails": true
    }
  ]
}

• ✅ Two-Way Data Binding: Changes in child components automatically update parent state
• 🔄 Reactive Updates: UI updates automatically when bound data changes
• 🎯 Type Safety: Full Swift type checking for binding properties
• 🚀 Performance: Efficient SwiftUI binding system with no overhead
• 📦 Seamless Integration: Works with existing SwiftJsonUI data binding system

The Ruby converter detects @{propertyName} syntax and generates:

UserProfile(
    user: $viewModel.data.currentUser,
    isEditing: $viewModel.data.editMode,
    showDetails: true
)

The adapter creates proper SwiftUI bindings from the ViewModel:

let userBinding = Binding(
    get: { viewModel.data.currentUser as? User ?? User() },
    set: { viewModel.data.currentUser = $0 }
)

• Fixed Ruby converter's handling of falsey boolean values (nil vs false)
• Improved binding expression detection in converter generator
• Enhanced adapter generation for proper SwiftUI.Binding support

Updated documentation includes:

• Comprehensive binding property examples in Converter Command docs
• Clear explanation of @ prefix syntax for attributes
• JSON binding syntax @{propertyName} usage
• Use cases for binding properties

No breaking changes. To use binding properties:

1. Update Package.swift:

dependencies: [
    .package(url: "https://github.com/Tai-Kimura/SwiftJsonUI.git", from: "7.1.1")
]

2. Start using binding properties:

sjui g converter MyComponent --attributes "@value:String,@isActive:Bool"

1. Use Bindings for Editable Data: Properties that users can modify should be bindings
2. Static for Display-Only: Use regular properties for read-only data
3. Consistent Naming: Use clear names that indicate the property's purpose
4. Type Safety: Always specify the correct type for binding properties

• Documentation: SwiftJsonUI Wiki
• Issues: GitHub Issues
• Examples: Custom Components Examples

SwiftJsonUI is developed and maintained by Tai Kimura