SwiftUI 列表 "Generic parameter 'S' could not be inferred"

Question

我正在尝试显示 SwiftUI 列表并收到错误，"Generic parameter 'S' could not be inferred"。我曾尝试将其更改为 ForEach，但在 ForEach 处出现相同的错误。错误的位置在下面有注释。

import SwiftUI
import Combine

@available(iOS 13.3, *)
struct MyCustomerListView: View {
    @ObservedObject var custObservable: CustomersObservable = CustomersObservable()

    init()
    {
        UITableView.appearance().tableHeaderView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: Double.leastNonzeroMagnitude))
    }

    var body: some View {
        List(custObservable.customers) { cust in  //  <-- Error is here on List
            NavigationLink(destination: MultipleSignatureView(customer: cust)) {
                Text(cust.companyName)
            }
        }.listStyle(GroupedListStyle())
    }
}

@available(iOS 13.3, *)
class CustomersObservable: ObservableObject {
    @Published var customers: [Cust] = [Cust]()

    init() {
        customers.append(contentsOf: [
            Cust(id: "u", companyName: "Uinta"),
            Cust(id: "v", companyName: "victor"),
            Cust(id: "w", companyName: "wasden")
        ])
    }
}

@available(iOS 13.3, *)
class Cust: Identifiable {
    var id: String
    var companyName: String

    init(id: String, companyName: String) {
        self.id = id
        self.companyName = companyName
    }
}

会是什么？提前致谢。

Answer 1

我终于明白了。该错误根本不直观。我的问题出在这段代码中：

NavigationLink(destination: MultipleSignatureView(customer: cust)) { // <-- wrong type passed
    Text(cust.companyName)
}

我的 MultipleSignatureView class 使用了 String 而不是 Cust 对象。一旦我对我的 MultipleSignatureView 构造函数进行了更改，允许它接收 Cust 对象，它就起作用了。

感谢那些发表评论的人。事后看来，由于我发布的代码是在其他系统上编译的，所以我的问题应该包括我的相关对象。如果有人有类似的问题，我会在这里提供我的前后代码：

之前：

import SwiftUI

@available(iOS 13.3, *)
struct MultipleSignatureView: View {
    var customer: String     // <-- It was choking here. Cust object was being passed
    var body: some View {
        Text(customer)
    }
}

之后：

import SwiftUI

@available(iOS 13.3, *)
struct MultipleSignatureView: View {
    var customer: Cust               // <-- Now it takes a Cust object
    var body: some View {
        Text(customer.companyName)
    }
}

SwiftUI 列表 "Generic parameter 'S' could not be inferred"

SwiftUI List "Generic parameter 'S' could not be inferred"

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