VisionPro所需的SwiftUI

struct ContentView: View {
    
    var body: some View {
        Text("Hello world")
        Image(systemName: "shareplay")
        .foregroundColor(.white)
        .frame(width: 28,height: 28)
    }
}

struct ContentView: View {
    
    var body: some View {
        let textView = Text("Hello world")
        let imageView = Image(systemName: "shareplay")
        .foregroundColor(.white)
        .frame(width: 28,height: 28)
        let container = View()
        container.addSubView(textView)
        container.addSubView(imageView)
        return container
    }
}

public protocol View {

    /// The type of view representing the body of this view.
    ///
    /// When you create a custom view, Swift infers this type from your
    /// implementation of the required ``View/body-swift.property`` property.
    associatedtype Body : View

    /// The content and behavior of the view.
    ///
    /// When you implement a custom view, you must implement a computed
    /// `body` property to provide the content for your view. Return a view
    /// that's composed of built-in views that SwiftUI provides, plus other
    /// composite views that you've already defined:
    ///
    ///     struct MyView: View {
    ///         var body: some View {
    ///             Text("Hello, World!")
    ///         }
    ///     }
    ///
    /// For more information about composing views and a view hierarchy,
    /// see <doc:Declaring-a-Custom-View>.
    @ViewBuilder @MainActor var body: Self.Body { get }
}

Text("Hello")
.padding()
.backgound(Color.blue)

Text("Hello") 
.background(Color.blue) 
.padding()

enum BGType:Int {
    case clear = 0
    case glass = 1
    case meterial = 2
    case pureColor = 3
}

extension View {
func dtBackgroundEffect(
        effectType:BGType = .clear
    ) -> some View {
        self.modifier(
            dtBackgroundEffectModifier(effectType: effectType)
        )
    }
}

private struct dtBackgroundEffectModifier: ViewModifier {
    var effectType:BGType = .clear
    func body(content: Content) -> some View {
        switch effectType {
        case .clear:
            content.background(.clear)
        case .glass:
            content
                .glassBackgroundEffect(displayMode: .always)
        case .meterial:
            content
                .background(.regularMaterial)
        case .pureColor:
            content
                .background(Color(uiColor: UIColor.dt_color(withHexString: "29231F")))
        }
    }
}

extension View {
func dtBackgroundEffect(
        effectType:BGType = .clear
    ) -> some View {
        var effectType:BGType = .clear
        switch effectType {
        case .clear:
            return self.background(.clear)
        case .glass:
            return self
                .glassBackgroundEffect(displayMode: .always)
        case .meterial:
            return self
                .background(.regularMaterial)
        case .pureColor:
            return self
                .background(Color(uiColor: UIColor.dt_color(withHexString: "29231F")))
        }
    }
}

@inlinable public func background<S>(_ style: S, ignoresSafeAreaEdges edges: Edge.Set = .all) -> some View where S : ShapeStyle

extension View {
@ViewBuilder
func dtBackgroundEffect(
        effectType:BGType = .clear
    ) -> some View {
        var effectType:BGType = .clear
        switch effectType {
        case .clear:
            self.background(.clear)
        case .glass:
            self
                .glassBackgroundEffect(displayMode: .always)
        case .meterial:
            self
                .background(.regularMaterial)
        case .pureColor:
            self
                .background(Color(uiColor: UIColor.dt_color(withHexString: "29231F")))
        }
    }
}

@state var showChinese = false
Text(showChinese ? "你好" : "Hello")
.padding()
.backgound(showChinese ? Color.red : Color.blue)

enum Animal { case dog,cat }

struct Pet:Identifiable {
    var name:String
    var kind:Animal
    var id: UUID { UUID() }
    var dataBaseID:Int
}

struct FavoritePets: View {
    var pets:[Pet]
    var body: some View {
        List {
            ForEach(pets) {
                PetView {$0}
            }
        }
    }
}

struct FavoritePets: View {
    var pets:[Pet]
    var body: some View {
        List {
            ForEach(pets,id:.\dataBaseID) {
                PetView {$0}
            }
        }
    }
}

import SwiftUI
import Combine

// 1. 定义全局数据源
class GlobalData: ObservableObject {
    @Published var counter: Int = 0
    static let shared = GlobalData() // 单例对象
}

struct ContentView: View {
    // 2. 订阅数据变化
    @ObservedObject var globalData = GlobalData.shared
    
    var body: some View {
        VStack {
            Text("Counter: \(globalData.counter)")
            Button("Increment") {
                GlobalData.shared.counter += 1 // 修改全局数据源的值
            }
        }
    }
}

@Observable
class GlobalData {
    var counter: Int = 0
    static let shared = GlobalData() // 单例对象
}

extension View {
    @available(iOS 17.0, macOS 14.0, tvOS 17.0, watchOS 10.0, *)
    public func environment<T>(_ object: T?) -> some View where T : AnyObject, T : Observable
}
struct ContentView: View {
    // 订阅数据变化
    @Environment(GlobalData.self) private var globalData: GlobalData
    
    var body: some View {
        VStack {
            Text("Counter: \(globalData.counter)")
            Button("Increment") {
                GlobalData.shared.counter += 1 // 修改全局数据源的值
            }
        }
    }
}

@Observable
class GlobalData {
    var counter: Int = 0
    @ObservationIgnored private var tempValue = false
    static let shared = GlobalData() // 单例对象
}