amazon-dynamodb - 如何在 SwiftUI 中使用 ObservableObject 加载数据？

Question

我正在尝试将一个应用程序从 UIKit 转换到 SwiftUI，这取决于基本的 DynamoDB 资源，但我在强制 View 在数据添加到列表时刷新时遇到了障碍。我在这组代码上花费了数小时尝试不同的事情，我想我可能会看看是否有人知道为什么“SessionsData”似乎被丢弃并且不会累积“Sessions”对象。

有没有人有任何快速的想法？？？

class SessionsData: ObservableObject {

    let didChange = PassthroughSubject<SessionsData, Never>()
    @Published var data: [Sessions] = [] {
        didSet {
            didChange.send(self)
        }
    }

    init() {
        load()
    }

    func load() {
        let dynamoDBObjectMapper = AWSDynamoDBObjectMapper.default()
        let scanExpression = AWSDynamoDBScanExpression()
        scanExpression.limit = 20

        var temp : [Sessions] = []

        dynamoDBObjectMapper.scan(Sessions.self, expression: scanExpression).continueWith(block: { (task:AWSTask<AWSDynamoDBPaginatedOutput>!) -> Any? in
            if let error = task.error as NSError? {
                 print("The request failed. Error: \(error)")
             } else if let paginatedOutput = task.result {
                for session in paginatedOutput.items as! [Sessions] {
                    print("Item Found")
                    temp.append(session)
                }
                DispatchQueue.main.async {
                    self.data = temp
                    self.didChange.send(self)
                }
             }
            print(self.data.count)
            return true
         })
    }
}

struct Events: View {

    @ObservedObject var sessionsData = SessionsData()


    var body: some View {...}
}

Answer 1

看起来您使代码过于复杂了。 PassthroughSubject 是不必要的。每当您更改 @Published 属性时，它都应该触发更新。

class SessionsData: ObservableObject {

    @Published var data: [Sessions] = []

    init() {
        load()
    }

    func load() {
        let dynamoDBObjectMapper = AWSDynamoDBObjectMapper.default()
        let scanExpression = AWSDynamoDBScanExpression()
        scanExpression.limit = 20

        var temp : [Sessions] = []

        dynamoDBObjectMapper.scan(Sessions.self, expression: scanExpression).continueWith(block: { (task:AWSTask<AWSDynamoDBPaginatedOutput>!) -> Any? in
            if let error = task.error as NSError? {
                 print("The request failed. Error: \(error)")
             } else if let paginatedOutput = task.result {
                for session in paginatedOutput.items as! [Sessions] {
                    print("Item Found")
                    temp.append(session)
                }
                DispatchQueue.main.async {
                    self.data = temp
                }
             }
            print(self.data.count)
            return true
         })
    }
}