[英]How to use Swift Codable with a nested JSON structure and unknown keys
我有一個嵌套的json結構。 我知道頂級鍵(對象),但每次獲取可能存在也可能不存在。 對象中的每個鍵(以及嵌套在其中的鍵)都是未知的。 他們很有活力。
我已經嘗試了幾個小時才使用Codable來代替使用JSONSerialization。 在我完全失去希望之前,我想看看是否有人有解決方案。
以下是我的JSON的示例:
var jsonString =
"""
{
"someNumbers": {
"22": 6,
"22626": 0
},
"someNestedAny": {
"61": {
"browser": 2
},
"8310": {
"desktop": 2
}
},
"someNestedArray": {
"49": ["Chrome"],
"50": ["Mac OS X"],
"51": ["Mac desktop"],
"52": ["browser"],
"53": ["Chrome"]
}
}
"""
每個頂級對象中的鍵值對(someNumbers,someNestedAny和someNestedArray是動態的。這些對象中的鍵/值也是動態的...依此類推。每個頂級對象也是可選的。
我嘗試了很多東西,但這些東西看起來最有希望(它們都不起作用,所以)
struct TopLevel: Decodable { var someNumbers: SomeNumbers? var someNestedAny: SomeNestedAny? var someNestedArray: SomeObjectFromNestedAny? } struct SomeNumbers: Decodable { var key: String var value: Int } struct SomeNestedAny: Decodable { var key: String var value: SomeObjectFromNestedAny } struct SomeObjectFromNestedAny: Decodable { var key: String var value: Int } struct SomeNestedArray: Decodable { var key: String var value: [String] } let data = jsonString.data(using: .utf8)! do { let result = try JSONDecoder().decode(TopLevel.self, from: data) print(result) } catch { print(error) }
輸出: keyNotFound(CodingKeys(stringValue: "key", intValue: nil), Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "someNumbers", intValue: nil)], debugDescription: "No value associated with key CodingKeys(stringValue: \\"key\\", intValue: nil) (\\"key\\").", underlyingError: nil))
struct TopLevel: Decodable { var someNumbers: SomeNumbers? var someNestedAny: SomeNestedAny? var someNestedArray: SomeObjectFromNestedAny? } struct SomeNumbers: Decodable { public var numbersObject: [String: NumberKeys] public struct NumberKeys: Decodable { public let key: String public let value: Int } private struct NumberCodingKeys: CodingKey { var stringValue: String init?(stringValue: String) { self.stringValue = stringValue } var intValue: Int? init?(intValue: Int) { return nil } } public init(from decoder: Decoder) throws { let container = try decoder.container(keyedBy: NumberCodingKeys.self) self.numbersObject = [String: NumberKeys]() for key in container.allKeys { let value = try container.decode(NumberKeys.self, forKey: NumberCodingKeys(stringValue: key.stringValue)!) self.numbersObject[key.stringValue] = value } } } struct SomeNestedAny: Decodable { // was going to do the same thing as above - but it didn't work var key: String var value: SomeObjectFromNestedAny } struct SomeObjectFromNestedAny: Decodable { // was going to do the same thing as above - but it didn't work var key: String var value: Int } struct SomeNestedArray: Decodable { // was going to do the same thing as above - but it didn't work var key: String var value: [String] } let data = jsonString.data(using: .utf8)! do { let result = try JSONDecoder().decode(TopLevel.self, from: data) print(result) } catch { print(error) }
輸出: typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "someNumbers", intValue: nil), NumberCodingKeys(stringValue: "22626", intValue: nil)], debugDescription: "Expected to decode Dictionary<String, Any> but found a number instead.", underlyingError: nil))
這是我現在的工作,但真的很重要:
let data = jsonString.data(using: .utf8)
let json = try JSONSerialization.jsonObject(with: data!) as! [String:Any]
if let numbers = json["someNumbers"] as? [String:Any] {
for (key, value) in numbers {
print("key: \(key), value: \(value)")
}
}
if let anys = json["someNestedAny"] as? [String: Any] {
//print("tkey: \(anys)")
for (key, value) in anys {
//print("tkey2: \(key), tvalue: \(value)")
if let value = value as? [String: Any] {
let anyData = try JSONSerialization.data(withJSONObject: value, options: .prettyPrinted)
let anyJson = try JSONSerialization.jsonObject(with: anyData) as! [String: Any]
for (key2, value2) in anyJson {
print("key: \(key), object-key: \(key2), object-value: \(value2)")
}
}
}
}
if let arrays = json["someNestedArray"] as? [String: Any] {
for (key, value) in arrays {
print("key: \(key), value: \(value)")
}
}
提前致謝!
很難說這是否能解決您的確切用例,因為我不確定數據的用途是什么,以及您預期如何使用它,但以下兩種解決方案都能正確地將您的JSON解碼為更有用的Swift對象。
最簡單的方法是將其建模為您呈現的數據結構。 例如,看起來someNumbers
是一個由String
鍵入的可選字典,其Int
值為: [String: Int]?
。
struct TopLevel: Decodable {
var someNumbers: [String: Int]?
var someNestedAny: [String: [String: Int]]?
var someNestedArray: [String: [String]]?
}
為了在傳遞對象時更加可讀性,可以引入一些類型的別名,它就變成了
typealias SomeNumbers = [String: Int]
typealias SomeNestedAny = [String: [String: Int]]
typealias SomeNestedArray = [String: [String]]
struct TopLevel: Decodable {
var someNumbers: SomeNumbers?
var someNestedAny: SomeNestedAny?
var someNestedArray: SomeNestedArray?
}
為了獲得有用的東西,你需要調用類似的東西
topLevel.someNumbers?["22"] // 6
topLevel.someNestedAny?["8310"] // ["desktop": 2]
topLevel.someNestedAny?["8310"]?["desktop"] // 2
topLevel.someNestedArray?["52"] // ["browser"]
topLevel.someNestedArray?["52"]?[0] // "browser"
或者根據您的需要,循環使用更有意義
topLevel.someNestedAny?
.forEach { item in
print("|- \(item.key)")
item.value.forEach { any in
print("| |- \(any.key)")
print("| | |- \(any.value)")
}
}
// |- 61
// | |- browser
// | | |- 2
// |- 8310
// | |- desktop
// | | |- 2
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