.onDrag

🌀 view.onDrag

// 🌀view.onDrag(changed: {}, ended: {})
extension View {
    public func onDrag(
        changed: @escaping (DragGesture.Value) -> Void,
        ended  : @escaping (DragGesture.Value) -> Void
    ) -> some View {
        let drag = DragGesture().onChanged(changed).onEnded(ended)
        return self.gesture(drag)
    }
}

💈 範例

import SwiftUI
import PlaygroundSupport

struct ContentView: View {
    // ⭐️ drag state
    @State private var translation = CGSize.zero
    var body: some View {
        VStack {
            Circle()
                .fill(Color.pink)
                .frame(44, 44)        // 🌀view.frame(w,h)
                // ⭐️ 2. follow drag
                .offset(translation)
                // ⭐️ 1. update state
                .onDrag(              // 🌀view.onDrag(changed: {}, ended: {})
                    changed: { self.translation = $0.translation },
                    ended  : { _ in self.translation = .zero     }
                )
        }// container
            .frame(400, 300)
            .padding()
            .shadow(radius: 8)
            .background(Color.gray)
            .cornerRadius(10)
    }
}

PlaygroundPage.current.setLiveView(ContentView())

不用外掛的寫法

struct ContentView: View {
    // ⭐️ drag state
    @State private var translation = CGSize.zero
    var body: some View {
        VStack {
            Circle()
                .fill(Color.pink)
                .frame(44, 44)        // 🌀View + frame(w,h)
                // ⭐️ 3. follow drag
                .offset(translation)
                .gesture(
                    DragGesture()
                        // ⭐️ 1. update state
                        .onChanged { self.translation = $0.translation }
                        // ⭐️ 2. reset (return to the original place)
                        .onEnded   { _ in self.translation = .zero     }
            )
        }// container
            .frame(400, 300)
            .padding()
            .shadow(radius: 8)
            .background(Color.gray)
            .cornerRadius(10)
    }
}

📘 參考

• Drag Gesture - Design + Code

🍎 官方

• SwiftUI ⟩ Gestures ⟩ DragGesture

  • onChanged(_:)

  • onEnded(_:)

  • DragGesture.Value

• SwiftUI ⟩ Views & Controls ⟩ Views ⟩ Input and Events

  • onTapGesture(count:perform:)