Question

我在我的视图中使用ObservableObject遇到数组问题。我有一个空数组。我在onAppear页面上调用一个函数。当数据返回时，视图不使用数组中的新数据更新：

consume

我认为这是

class NewsState: ObservableObject {

    private let base: String = "api"
    let objectWillChange = ObservableObjectPublisher()

    @Published var wagsList: Array<UserSlider> = [] {
        willSet {
            objectWillChange.send()
        }
    }

    func getList() {
        let url = NSURL(string: "\(base)/UserApi/getList")
        var mutableURLRequest = URLRequest(url: url! as URL)
        mutableURLRequest.httpMethod = "GET"
        mutableURLRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
        AF.request(mutableURLRequest).responseData { response in
            guard let data = response.data else { return }
            let resp = try! JSONDecoder().decode(Array<UserSlider>.self, from: data)
            for i in resp {
                let userSlider = UserSlider(id: i.id, uid: i.uid, image: i.image)
                self.wagsList.append(userSlider)
            }
        }
    }
}

我错了哪里？我已经看到问题是由ScrollView引起的

Answer 1

尝试这个

class NewsState: ObservableObject {

    private let base: String = "api"

    @Published var wagsList: Array<UserSlider> = []

    func getList() {
        let url = NSURL(string: "\(base)/UserApi/getList")
        var mutableURLRequest = URLRequest(url: url! as URL)
        mutableURLRequest.httpMethod = "GET"
        mutableURLRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
        AF.request(mutableURLRequest).responseData { response in
            guard let data = response.data else { return }
            let resp = try! JSONDecoder().decode(Array<UserSlider>.self, from: data)

            let results = resp.map { UserSlider(id: $0.id, uid: $0.uid, image: $0.image) }
            DispatchQueue.main.async {
                self.wagsList = results
            }
        }
    }
}

Answer 2

由于我不清楚错误可能在哪里。它可以在getList中或您的视图中。

这是一个如何与Published和ObserverdObject一起工作的简单示例：注意：您的getList函数不在此解决方案中，因为您的API，JSON ect可能会出错。

import SwiftUI

struct ContentView: View {

    @ObservedObject var state = NewsState()

    var body: some View {
        Group { //needed for the IF Statement below
            if state.stringList.count > 0 {
                ForEach(self.state.stringList, id: \.self){ s in
                    Text(String(s))
                }
            }
        }.onTapGesture {
            self.state.getNewList()
        }
    }
}

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


class NewsState: ObservableObject {

    @Published var stringList: Array<String> = []

    init() {
        self.getList()
    }

    func getList() {
        self.stringList.append("New")
    }

    func getNewList() {
        self.stringList = []
        self.stringList.append("New new")
    }
}

Swiftui ObservableObject与数组不更新视图

2 个答案: