Listメモ

Listで選択された要素の取得
複数選択にする例

Listで選択された要素の取得

List(_:selection:) ＋ Identifiable.ID を使う

@State private var selectedID: ScreenshotItem.ID?

List(items, selection: $selectedID) { item in
    Text("item")
}

@State private var selectedID: ScreenshotItem.ID?

List(items, selection: $selectedID) { item in

Text("item")

}

モデル

struct ScreenshotItem: Identifiable, Hashable {
    let id = UUID()
    let cgImage: CGImage
}

struct ScreenshotItem: Identifiable, Hashable {

let id = UUID()

let cgImage: CGImage

}

View

@State private var screenshots: [ScreenshotItem] = []
@State private var selectedID: ScreenshotItem.ID?

List(screenshots, selection: $selectedID) { item in
    Image(decorative: item.cgImage, scale: 2.0)
        .resizable()
        .scaledToFit()
        .frame(height: 80)
}
.listStyle(.sidebar)

@State private var screenshots: [ScreenshotItem] = []

@State private var selectedID: ScreenshotItem.ID?

List(screenshots, selection: $selectedID) { item in

Image(decorative: item.cgImage, scale: 2.0)

.resizable()

.scaledToFit()

.frame(height: 80)

}

.listStyle(.sidebar)

選択された「実体」を取得

var selectedItem: ScreenshotItem? {
    screenshots.first { $0.id == selectedID }
}

var selectedItem: ScreenshotItem? {

screenshots.first { $0.id == selectedID }

}

複数選択の場合

@State private var selection = Set<ScreenshotItem.ID>()

List(screenshots, selection: $selection) { item in
    Text("SS")
}

@State private var selection = Set<ScreenshotItem.ID>()

List(screenshots, selection: $selection) { item in

Text("SS")

}

実体取得

let selectedItems = screenshots.filter {
    selection.contains($0.id)
}

let selectedItems = screenshots.filter {

selection.contains($0.id)

}

「クリック時に即処理したい」場合

onChange を使う

.onChange(of: selectedID) { _, newValue in
    guard let id = newValue else { return }
    let item = screenshots.first { $0.id == id }
    // メインに反映、加工開始など
}

.onChange(of: selectedID) { _, newValue in

guard let id = newValue else { return }

let item = screenshots.first { $0.id == id }

// メインに反映、加工開始など

}

選択された要素の削除の例

Button(action: {
    guard let id = selected_item else { return }

    // 選択されている要素を削除
    SS_images.removeAll { $0.id == id }

    // 選択状態をクリア
    selected_item = nil
    image = nil
}) {
    Image(systemName: "trash.circle")
        .resizable()
        .foregroundColor(Color(.blue))
        .frame(width: 20, height: 20)
}

Button(action: {

guard let id = selected_item else { return }

// 選択されている要素を削除

SS_images.removeAll { $0.id == id }

// 選択状態をクリア

selected_item = nil

image = nil

}) {

Image(systemName: "trash.circle")

.resizable()

.foregroundColor(Color(.blue))

.frame(width: 20, height: 20)

}

複数選択にする例

複数選択を有効にするには、Listに.selectionDisabled(false)を追加するだけでは不十分です。以下の修正が必要です：

修正箇所

struct ScreenshotSidebarView: View {
    @Binding var capture_image: CGImage?
    @Binding var SS_images: [ScreenshotItem]
    @Binding var selected_item: Set<ScreenshotItem.ID>  // ← ? を削除（常にSetを持つ）
    @State private var trash_flg: Bool = false
    
    var selected_image: CGImage? {
        guard let firstID = selected_item.first else { return nil }  // ← selected_itemは常にSetなので guard let 不要
        return SS_images.first { $0.id == firstID }?.cg_image
    }
    
    var multiple_selected_image: [ScreenshotItem] {
        return SS_images.filter { selected_item.contains($0.id) }  // ← シンプルに
    }
    
    var body: some View {
        HStack {
            List(SS_images, selection: $selected_item) { item in
                Image(decorative: item.cg_image, scale: 2.0)
                    .resizable()
                    .scaledToFit()
                    .frame(height: 80)
                    .padding(4)
            }
            .listStyle(.sidebar)
            // ← ここに何も追加しなくてOK

struct ScreenshotSidebarView: View {

@Binding var capture_image: CGImage?

@Binding var SS_images: [ScreenshotItem]

@Binding var selected_item: Set<ScreenshotItem.ID> // ← ? を削除（常にSetを持つ）

@State private var trash_flg: Bool = false

var selected_image: CGImage? {

guard let firstID = selected_item.first else { return nil } // ← selected_itemは常にSetなので guard let 不要

return SS_images.first { $0.id == firstID }?.cg_image

}

var multiple_selected_image: [ScreenshotItem] {

return SS_images.filter { selected_item.contains($0.id) } // ← シンプルに

}

var body: some View {

HStack {

List(SS_images, selection: $selected_item) { item in

Image(decorative: item.cg_image, scale: 2.0)

.resizable()

.scaledToFit()

.frame(height: 80)

.padding(4)

}

.listStyle(.sidebar)

// ← ここに何も追加しなくてOK

重要なポイント

@Binding var selected_item: Set<ScreenshotItem.ID>
macOSでは自動的に複数選択が有効
ScreenshotItemがIdentifiableに準拠している必要がある

struct ScreenshotItem: Identifiable {
       let id: UUID
       let cg_image: CGImage
       // ...
   }

struct ScreenshotItem: Identifiable {

let id: UUID

let cg_image: CGImage

// ...

}

親ビューでの使い方

struct ParentView: View {
    @State private var SS_images: [ScreenshotItem] = []
    @State private var selected_item: Set<ScreenshotItem.ID> = []  // ← 空のSetで初期化
    @State private var capture_image: CGImage?
    
    var body: some View {
        ScreenshotSidebarView(
            capture_image: $capture_image,
            SS_images: $SS_images,
            selected_item: $selected_item
        )
    }
}

struct ParentView: View {

@State private var SS_images: [ScreenshotItem] = []

@State private var selected_item: Set<ScreenshotItem.ID> = [] // ← 空のSetで初期化

@State private var capture_image: CGImage?

var body: some View {

ScreenshotSidebarView(

capture_image: $capture_image,

SS_images: $SS_images,

selected_item: $selected_item

)

}

選択状態の確認

// 選択数を表示
Text("選択数: \(selected_item.count)")

// 選択されているか確認
if !selected_item.isEmpty {
    Text("選択中")
}

// 選択数を表示

Text("選択数: \(selected_item.count)")

// 選択されているか確認

if !selected_item.isEmpty {

Text("選択中")

}

これでCommandキーやShiftキーを使った複数選択ができるようになります！試してみてください。