ios - 如何修复 TextField 绑定在 SwiftUI 中显示和编辑

Question

我想在其中显示文本TextField并能够对其进行编辑。但是我在绑定它时遇到了问题。这是我的代码：

struct DataView: View {
@ObservedObject private var dataPresenter = DataPresenter()

var body: some View {
    VStack {
        TextField("Name", text: $dataPresenter.data?.name ?? "") // This is the error

    }
        .onAppear(perform: {
            dataPresenter.getData()
        })
     }
}

class DataPresenter: ObservableObject {
@Injected private var getDataInteractor: GetDataInteractor
@Injected private var cancellables: Set<AnyCancellable>
@Published var data: GetDataResp?

func getData() {
    getDataInteractor.execute()
        .sink { error in
            print("Error:", error)
        } receiveValue: { response in
            if response.errorCode == "00" {
                print(response)
                self.data = response
            }
        }
        .store(in: &cancellables)
     }
}

struct GetDataResp: Codable, Equatable {
     var name : String?
     var address : String?
     var email : String?

enum CodingKeys: String, CodingKey {
        case name = "name"
        case address = "address"
        case email = "email"
     }

init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        name = try values.decodeIfPresent(String.self, forKey: .name)
        address = try values.decodeIfPresent(String.self, forKey: .address)
        email = try values.decodeIfPresent(String.self, forKey: .email)      
    }
}

当我不使用?in 时$dataPresenter.data.name ?? ""，我总是会收到这样的错误：

然后，当我用 修复它时?，我会收到更多这样的错误：

我陷入了这个错误循环，使用force unwrap会使应用程序崩溃。我有比名字更多的变量，所以我不能只self.name = response.name ?? ""在响应中。我怎么能解决这个问题？

任何建议，将不胜感激。

标签： iosswiftuibindingtextfieldoptional

Answer 1

TextField需要一个，而Binding不仅仅是一个String。因此，当您""在Binding为 nil 的情况下提供它时，您最终会得到非等效类型（Binding<String>vs String）。

要解决这个问题，您可能需要创建一个自定义绑定来处理存在的data情况nil。

这是一种可能的解决方案：

struct DataView: View {
    
    @ObservedObject private var dataPresenter = DataPresenter()
    
    var body: some View {
        VStack {
            Text(dataPresenter.data?.name ?? "Empty")
            TextField("Name", text: dataPresenter.nonOptionalNameBinding())
        }
    }
}

struct GetDataResp {
    var name : String
}

class DataPresenter: ObservableObject {
    @Published var data: GetDataResp?
    
    func nonOptionalNameBinding() -> Binding<String> {
        .init {
            return self.data?.name ?? ""
        } set: { newValue in
            if self.data == nil {
                self.data = GetDataResp(name: newValue)
            } else {
                self.data?.name = newValue
            }
        }
    }
}

您可能需要根据您的需要以不同方式处理本set:节中的情况。而且，当然，我 stubbed GetDataResp，我假设它比我在那里的更详细，但这应该让你开始。

---

更新，基于评论：

struct GetDataResp: Codable, Equatable {
     var name : String?
     var address : String?
     var email : String?
}

struct DataView: View {
    @ObservedObject private var dataPresenter = DataPresenter()
    
    var body: some View {
        VStack {
            Text(dataPresenter.data?.name ?? "Empty")
            TextField("Name", text: dataPresenter.nonOptionalBinding(keyPath: \.name))
            TextField("Address", text: dataPresenter.nonOptionalBinding(keyPath: \.address))
            TextField("Email", text: dataPresenter.nonOptionalBinding(keyPath: \.email))
        }
    }
}


class DataPresenter: ObservableObject {
    @Published var data: GetDataResp?
    
    func nonOptionalBinding(keyPath: WritableKeyPath<GetDataResp,String?>) -> Binding<String> {
        .init {
            return self.data?[keyPath: keyPath] ?? ""
        } set: { newValue in
            if self.data == nil {
                self.data = GetDataResp()
            }
            self.data?[keyPath: keyPath] = newValue
        }
    }
}