需要帮助以使NavigationLink在SwiftUI中工作

问题描述

我目前正在通过www.hackingwithswift.com学习Swift和SwiftUI，目前正在进行编码练习，并且无法使我的ContentView使用NavigationLink链接到另一个SwiftUI视图。

如果我将目的地替换为一些随机文本，则可以使用。当我尝试将我的SwiftUI视图插入为目标时，代码将中断。我看了一个接一个的视频，但我不明白为什么我的代码无法正常工作。以下是我的ContentView和SwiftUI视图（名为：UserView.swift）的代码。我认为这与UserView_Previews有关，但我不确定。任何帮助/想法/建议将不胜感激！

ContentView代码

struct ContentView: View {
    @State private var results = [User]()
    
    var body: some View {
        NavigationView {
            List(results,id: \.id) {item in
                NavigationLink(destination: UserView(results: results)) {
                    vstack(alignment: .leading) {
                        Text(item.name)
                            .font(.headline)
                        Text("Age: \(item.age)")
                            .foregroundColor(Color.red)
                    }
                }
            }
        .onAppear(perform: loadData)
        }
    }
    
    func loadData() {
        guard let url = URL(string: "https://www.hackingwithswift.com/samples/friendface.json") else {
            print("Invalid URL")
            return
        }
        
        let request = URLRequest(url: url)
        
        URLSession.shared.dataTask(with: request) { data,response,error in
            if let data = data {
                dispatchQueue.main.async {
                    do {
                        self.results = try JSONDecoder().decode([User].self,from: data)
                    } catch {
                        print(error)
                    }
                }
            }
        }.resume()
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

UserView.swift

import SwiftUI

struct UserView: View {
    let results: User
    
    var body: some View {
        ScrollView(.vertical) {
            vstack {
                Text(results.email)
                    .font(.headline)
                Text(results.address)
                
            }
        }
    }
}

struct UserView_Previews: PreviewProvider {
    static let results = User(id: "123",isActive: true,name: "Cody",age: 34,company: "Some Company",email: "Some Email",address: "Some Address",about: "About Me",registered: "Yes",tags: ["1","2"],friends: [User.Friend(id: "456",name: "Some Friend Name")])
    
    static var previews: some View {
        UserView(results: results)
    }
}

UserFile.swift这是要构建我的User结构

import Foundation

struct User: Codable,Identifiable {
    let id: String
    let isActive: Bool
    let name: String
    let age: Int
    let company: String
    let email: String
    let address: String
    let about: String
    let registered: String
    let tags: [String]
    let friends: [Friend]
    
    struct Friend: Codable {
        let id: String
        let name: String
    }
}

解决方法

您的<properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions> <exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId> </exclusion> </exclusions> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> 在List的{​​{1}}上进行迭代，因此results是[User]，应将其传递给item期望只有一个User，而不是UserView()的数组。

User

---

我认为这与UserView_Previews有关，但我不确定。

User只是单元测试数据，它使您可以在Xcode的“预览”窗格中测试var body: some View { NavigationView { List(results,id: \.id) { item in NavigationLink(destination: UserView(results: item)) { // here VStack(alignment: .leading) { Text(item.name) .font(.headline) Text("Age: \(item.age)") .foregroundColor(Color.red) } } } .onAppear(perform: loadData) } } User_Previews。构建时不使用它。