MacOSswiftUI表格選擇單項

我按照這里的例子：SwiftUI 3 MacOs Table single selection and double click open sheet

但這對我來說效果不佳。

我有這樣的結構：

struct Response: Codable {
    var items: [Repository]
}

struct Repository: Codable, Identifiable {
    var number = UUID()
    var id: Int = 0
    let name: String
    let updated_at: String
    let owner: Owner
    let stargazers_count: Int
    let forks_count: Int
    let language: String?
    let description: String?

    struct Owner: Codable {
        let login: String
    }

    enum CodingKeys: String, CodingKey {
        case name, updated_at, owner, stargazers_count, forks_count, language, description
    }
}

class Api : ObservableObject{
    func loadData(query: String = "javascript", completion:@escaping ([Repository]) -> ()) {
        guard let url = URL(string: "https://api.github.com/search/repositories?q=\(query)") else {
            print("Invalid url...")
            return
        }
        URLSession.shared.dataTask(with: url) { data, response, error in
            if let decodedResponse = try? JSONDecoder().decode(Response.self, from: data!) {
                var id = 0
                let results = decodedResponse.items.map { (repo: Repository) -> Repository in
                    var copyRepo = repo
                    copyRepo.id = id
                    id  = 1
                    return copyRepo
                }
                print(results)
                DispatchQueue.main.async {
                    completion(results)
                }
            }
        }.resume()

    }
}


...

    @State var repositories = [Repository]()

    @State private var sortOrder = [KeyPathComparator(\Repository.name)]
    @State private var selectedRepository: Repository.ID?

    public var body: some View {

         if(selectedRepository != nil)//null??
         Text(repositories[selectedRepository!].name)

Table(repositories, selection: $selectedRepository, sortOrder: $sortOrder) {
                    TableColumn("Name") {
                        Text($0.name)
                            .frame(
                                maxWidth: .infinity,
                                maxHeight: .infinity,
                                alignment: .leading
                            )
                            .contentShape(Rectangle())
                            .contextMenu {
                                Button(action: {}) { Text("Action") }
                            }
                            /*.gesture(TapGesture(count: 2).onEnded {
                                print("pr", selectedRepository )
                            })*/
                    }

                    TableColumn("Last updated"){
                        Text($0.updated_at)
                    }
                    TableColumn("Owner", value: \.owner.login)
                }
                .onAppear() {
                    Api().loadData { (repositories) in
                        self.repositories = repositories
                        self.isLoading = false
                    }
                }
                .onChange(of: sortOrder) {
                    print($0)
                    repositories.sort(using: $0)
                }

    }

我想確保當用戶單擊表格的一個元素，然后激活選擇以在文本欄位中顯示所選元素的資料時，我試圖列印名稱但它不起作用。

啟動應用程式后，它給了我以下錯誤：Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

你能幫我個忙嗎？

uj5u.com熱心網友回復：

可能是一些缺失的字符：

if(selectedRepository != nil)//null?? <- missing '{'
    Text(repositories[selectedRepository!].name)

也可以這樣寫：

if let selectedRepository = selectedRepository {
    Text(repositories[selectedRepository!].name)
    ...
}

即使沒有必要，我總是更喜歡初始化屬性（這更像是一種有用的習慣）：

@State private var selectedRepository: Repository.ID? = nil

標籤：迅速 代码 苹果系统 迅捷 xcode13

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