使用自定义类型标识符进行拖放操作不起作用 [英] Drag and drop with custom type identifier doesn't work

问题描述

我正在尝试使用自定义类型标识符在macOS上实现拖放，以避免发生冲突，但这似乎不起作用.首先，这是一个具有 public 和已知标识符的工作示例:

I'm trying to achieve drag and drop on macOS with a custom type identifier to avoid collisions but it doesn't seem to work. First, here's a working example with a public and known identifier:

struct ReleaseView: View {
    let id: Int

    var body: some View {
        GeometryReader { _ in
            VStack(spacing: 16) {
                Image(nsImage: NSImage(named: NSImage.networkName)!)
                    .contentShape(Rectangle())
                    .onDrag {
                        return NSItemProvider(item: "\(self.id)" as NSString, typeIdentifier: NSPasteboard.PasteboardType.string.rawValue)
                    }

                DropZone()
            }
        }
    }
}

struct DropZone: View {
    @State var isDragging = false

    var body: some View {
        RoundedRectangle(cornerRadius: 16)
            .stroke(style: StrokeStyle(lineWidth: 4, dash: [8, 8]))
            .background(isDragging ? Color.secondary : Color.clear)
            .frame(width: 100, height: 100)
            .onDrop(of: [NSPasteboard.PasteboardType.string.rawValue], isTargeted: self.$isDragging) { itemProvider in
                print(itemProvider)
                return true
            }
    }
}

在此示例中，您可以将上面的图像拖动到放置区域中，它将打印出提供程序.现在，仅更改typeIdentifier会破坏一切.

In this example, you can drag the image above into the drop zone and it will print out the provider. Now, merely changing the typeIdentifier breaks everything.

static let sharedTypeIdentifier = "com.procrastin8.plzwork"

struct ReleaseView: View {
    // skipping the unchanged bits

                    .onDrag {
                        return NSItemProvider(item: "\(self.id)" as NSString, typeIdentifier: sharedTypeIdentifier)
                    }
}

struct DropZone: View {
    // skipping the unchanged bits

           .onDrop(of: [sharedTypeIdentifier], isTargeted: self.$isDragging) { itemProvider in
                print(itemProvider)
                return true
            }
}

现在这不起作用.在这里使用相同的常量，因此它不是字符串不匹配.只是另一个SwiftUI错误?

Now this doesn't work. Using the same constant here, so it's not a string mismatch. Just yet another SwiftUI bug?

推荐答案

上面的typeIdentifier不仅仅是唯一的字符串，它必须是UTI .

The typeIdentifier in above is not just a unique string, it must be UTI.

如果您要使用某些自定义应用程序的UTI(如果确实需要，请三思而后行)，则必须根据Apple规则从

If you want to use some custom-application-specifc UTI (think twice if you really need it), then you have to register one according to Apple rules, starting from

<key>UTExportedTypeDeclarations</key>
        <array>
            <dict>
                <key>UTTypeIdentifier</key>
                <string>com.procrastin8.plzwork</string>
                ...

在应用程序Info.plist

在 技术问答QA1796

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