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SwiftUI List“无法推断泛型参数'S'”

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dwaz · 技术社区 · 5 年前

我正在尝试显示一个SwiftUI列表并得到错误,“无法推断泛型参数”。我试着把它改成ForEach,但是在ForEach上得到了相同的错误。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
    }
}

0 回复 | 直到 5 年前

1

0

dwaz 5 年前

我终于明白了。这个错误一点也不直观。我的问题在于这个代码:

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

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)
    }
}