无法使用 UIViewRepresentable 和 UIDocumentPicker 选择文件夹

Question

我正在尝试为用户创建一个选择器，以便在 SwiftUI 应用程序中选择一个文件夹。但是，似乎还没有任何 SwiftUI 文档选择器，因此我尝试使用UIViewRepresentable 来显示使用此处概述的文件夹文档选择器的文档选择器：https://developer.apple.com/documentation/uikit/view_controllers/providing_access_to_directories。但是，如下图所示，我实际上无法以任何方式选择文件夹 - 我是否缺少将选择器与 SwiftUI 一起使用的特定内容？

FolderPicker代码：

struct FolderPicker: UIViewControllerRepresentable {
    @Binding var folderURL: String?
    
    func makeCoordinator() -> Coordinator {
        return FolderPicker.Coordinator(parent: self)
    }
    
    func makeUIViewController(context: UIViewControllerRepresentableContext<FolderPicker>) -> UIDocumentPickerViewController {
        let picker = UIDocumentPickerViewController(documentTypes: ["kUTTypeFolder"], in: .import)
        picker.delegate = context.coordinator
        return picker
    }
    
    func updateUIViewController(_ uiViewController: UIDocumentPickerViewController, context: UIViewControllerRepresentableContext<FolderPicker>) {}
    
    class Coordinator: NSObject, UIDocumentPickerDelegate {
        var parent: FolderPicker
        
        init(parent: FolderPicker) {
            self.parent = parent
        }
        
        internal func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentAt url: URL){
            print(url)
            parent.folderURL = url.absoluteString
        }
    }
}

在TestView:

struct TestView: View {
    @State var displayPicker = false

    var body: some View {
        Button(action: {displayPicker.toggle}, label: "toggle")
            .sheet(isPresented: $showPicker) {
                FolderPicker(folderURL: $url)
            }
    }
}

Answer 1

kUTTypeFolder 不是字符串。

正确的做法是

let picker = UIDocumentPickerViewController(documentTypes: [kUTTypeFolder as String], in: .import)

常量kUTTypeFolder 来自import CoreServices。

另外，public init(documentTypes allowedUTIs: [String], in mode: UIDocumentPickerMode) 和 optional func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentAt url: URL) 已弃用

所以使用public convenience init(forOpeningContentTypes contentTypes: [UTType]) 和optional func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL])

最终代码是：

struct FolderPicker: UIViewControllerRepresentable {
    
    @Binding var folderURL: String?
    
    func makeCoordinator() -> Coordinator {
        return FolderPicker.Coordinator(parent: self)
    }
    
    func makeUIViewController(context: UIViewControllerRepresentableContext<FolderPicker>) -> UIDocumentPickerViewController {
        let picker = UIDocumentPickerViewController(forOpeningContentTypes: [.folder])
        picker.delegate = context.coordinator
        return picker
    }
    
    func updateUIViewController(_ uiViewController: UIDocumentPickerViewController, context: UIViewControllerRepresentableContext<FolderPicker>) {}
    
    class Coordinator: NSObject, UIDocumentPickerDelegate {
        var parent: FolderPicker
        
        init(parent: FolderPicker) {
            self.parent = parent
        }
        func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
            guard let url = urls.first else {
                return
            }
            print(url)
            parent.folderURL = url.absoluteString
        }
    }
}