【SwiftUI】.contentTransition(.symbolEffect(.replace)) 👉 https://android.benigumo.com/20240509/contenttransition/

TestSymbolTransition.swift

import SwiftUI

struct TestSymbolTransition: View {
  @State private var value = true

  var body: some View {
    VStack {

      Button {
        value.toggle()
      } label: {
        Label("Favorite", systemImage: value ? "heart.fill" : "heart")
      }

      Button {
        value.toggle()
      } label: {
        Label("Favorite", systemImage: "heart")
          .symbolVariant(value ? .fill : .none)
      }

      Button {
        value.toggle()
      } label: {
        Label("Favorite", systemImage: "heart")
          .symbolVariant(value ? .fill : .none)
          .contentTransition(.symbolEffect(.replace))
      }

      Button {
        value.toggle()
      } label: {
        Label("Favorite", systemImage: "heart")
          .symbolVariant(value ? .fill : .none)
          .contentTransition(
            .symbolEffect(value ? .replace.upUp : .replace.downUp)
          )
      }

    }
    .buttonBorderShape(.capsule)
    .buttonStyle(.borderedProminent)
    .tint(.pink)

  }
}

#Preview {
  BackgroundCheckeredPattern {
    TestSymbolTransition()
  }
}