加载两个字典数组的json文件。将缺少的词典从文件A添加到文件B.

Question

我需要同步两个json文件，以便在应用更新后将文件A（位于应用包中）的新内容添加到文件B.

两个json文件都是字典数组。我需要迭代文件A的字典，并基于“id”值，如果文件B中不存在字典，我需要附加那些缺少的字典并将文件B保存回文件系统。

我有一个下面的解决方案，这样做，似乎工作。但它太难看了！当然，我把它放在一起大约15分钟，但是我确信必须有一个更好的方法来解决这个问题。此外，我不想通过将这些词典转换为结构或模型进行比较来进一步混淆水域，只是将它们转换回字典 - > json。

这里的任何建议都会很棒！我更喜欢干净的代码，这是一个烂摊子。

typealias JSON = [[String: Any]]
static private func uglySync() {
    let fileName: String = "someFileName"
    guard let sourceUrl = Bundle.main.url(forResource: fileName, withExtension: "json") else { return }
    guard let destinationDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
    let destinationUrl = destinationDirectory.appendingPathComponent("Data/" + fileName + ".json")

    do {
        let sourceData = try Data(contentsOf: sourceUrl)
        do {
            if let sourceArray = try JSONSerialization.jsonObject(with: sourceData, options: .mutableContainers) as? JSON {
                do {
                    let destinationData = try Data(contentsOf:  destinationUrl)
                    do {
                        if let destinationArray = try JSONSerialization.jsonObject(with: destinationData, options: .mutableContainers) as? JSON {
                            var mutableArray = destinationArray
                            sourceArray.forEach({ (item) in
                                if let itemId = item["id"] as? String {
                                    let foundItem = destinationArray.filter { $0["id"] as! String == itemId }.first
                                    if foundItem == nil {
                                        mutableArray.append(item)
                                    }
                                }
                            })

                            do {
                                let jsonData = try JSONSerialization.data(withJSONObject: mutableArray, options: .prettyPrinted)
                                try jsonData.write(to: destinationUrl)
                            } catch let error as NSError {
                                print("Couldn't write to file: \(error.localizedDescription)")
                            }
                        } else {
                            print("Cound not process json")
                        }
                    } catch {
                        print(error.localizedDescription)
                    }
                } catch {
                    print(error.localizedDescription)
                }
            } else {
                print("Cound not process json")
            }
        } catch {
            print(error.localizedDescription)
        }
    } catch {
        print(error.localizedDescription)
    }

    // oh wow the try catches :/
}

Answer 1

我已经将文件分组转换为jsonArray以简化do ... catch。或者，如果您不需要打印错误消息，您可以选择使用Optional try?来删除do ... catch块。

typealias JSONArray = [[String: Any]]

private func jsonArray(from fileURL: URL) -> JSONArray? {
    do {
        let fileData: Data = try Data(contentsOf: fileURL)
        guard let jsonArray = (try JSONSerialization.jsonObject(with: fileData, options: .mutableContainers)) as? JSONArray else {
            debugPrint("Failed to find JSON Array table")
            return nil
        }

        return jsonArray
    } catch {
        print(error.localizedDescription)
        return nil
    }
}

func sync() {
    let fileName: String = "someFileName"

    guard
        let fileURL: URL = Bundle.main.url(forResource: fileName, withExtension: "json"),
        let destinationDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first,
        let destinationURL: URL = destinationDirectory.appendingPathComponent("Data/" + fileName + ".json"),
        let sourceArray = jsonArray(from: fileURL),
        let destinationArray = jsonArray(from: destinationURL)
    else {
        return
    }

    var mutableArray = destinationArray
    let destinationIDArray = destinationArray.compactMap { $0["id"] as? String }

    mutableArray.forEach { (item) in
        if let itemId = item["id"] as? String, !(destinationIDArray.contains { $0 == itemId }) {
            mutableArray.append(item)
        }
    }

    // Update File
    do {
        let jsonData = try JSONSerialization.data(withJSONObject: mutableArray, options: .prettyPrinted)
        try jsonData.write(to: destinationURL)
    } catch {
        print("Couldn't write to file: \(error.localizedDescription)")
    }
}

Answer 2

我想你可以将不同的trys放在同一个do区块中。

do {
  try function1()
  try function2()
} catch {
  print(error.localizedDescription)
}

所以之后你的功能可能会像

    typealias JSON = [[String: Any]]
    static private func moderatelyOkSync() {
        let fileName: String = "someFileName"
        guard let sourceUrl = Bundle.main.url(forResource: fileName, withExtension: "json") else { return }
        guard let destinationDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
        let destinationUrl = destinationDirectory.appendingPathComponent("Data/" + fileName + ".json")

        do {
            let sourceData = try Data(contentsOf: sourceUrl)
            if let sourceArray = try JSONSerialization.jsonObject(with: sourceData, options: .mutableContainers) as? JSON {
                let destinationData = try Data(contentsOf:  destinationUrl)
            }
            var mutableArray = destinationArray
            sourceArray.forEach({ (item) in
                if let itemId = item["id"] as? String {
                    let foundItem = destinationArray.filter { $0["id"] as! String == itemId }.first
                    if foundItem == nil {
                        mutableArray.append(item)
                    }
                }
            })
            let jsonData = try JSONSerialization.data(withJSONObject: mutableArray, options: .prettyPrinted)
            try jsonData.write(to: destinationUrl)

        } catch {
            print(error.localizedDescription)
        }

    }

Answer 3

我这样做的方法是使用struct解码json文件，然后将其编码（序列化）到其他文件。因为执行此操作的代码将是2个衬里，但您首先必须布局结构中的所有变量。可能仍然不是最佳的