以下是这个类:
class User: NSManagedObject {
@NSManaged var id: Int
@NSManaged var name: String
}
需要转换为
{
"id" : 98,
"name" : "Jon Doe"
}
我曾尝试手动将对象传递给一个函数,该函数将变量设置为字典并返回字典。但我想有更好的方法来完成这个任务。
以下是这个类:
class User: NSManagedObject {
@NSManaged var id: Int
@NSManaged var name: String
}
需要转换为
{
"id" : 98,
"name" : "Jon Doe"
}
我曾尝试手动将对象传递给一个函数,该函数将变量设置为字典并返回字典。但我想有更好的方法来完成这个任务。
在 Swift 4 中,你可以继承自 Codable
类型。
struct Dog: Codable {
var name: String
var owner: String
}
// Encode
let dog = Dog(name: "Rex", owner: "Etgar")
let jsonEncoder = JSONEncoder()
let jsonData = try jsonEncoder.encode(dog)
let json = String(data: jsonData, encoding: String.Encoding.utf8)
// Decode
let jsonDecoder = JSONDecoder()
let secondDog = try jsonDecoder.decode(Dog.self, from: jsonData)
class
(我需要的)而不是 struct
。 - gondolet jsonData = jsonString.data(using: .utf8)!
let decoder = JSONDecoder()
let myStruct = try! decoder.decode(myStruct.self, from: jsonData)
将Swift对象转换为JSON字符串
let encoder = JSONEncoder()
encoder.outputFormatting = .prettyPrinted
let data = try! encoder.encode(myStruct)
print(String(data: data, encoding: .utf8)!)
您可以在此处找到所有细节和示例 使用 Swift 4 的 JSON 解析终极指南
更新: Swift 4中引入的Codable
协议对于大多数JSON
解析案例应该已经足够了。以下答案适用于那些被困在早期Swift版本和需要支持旧代码的人。
NSDictionary
、NSCoding
、Printable
、Hashable
和Equatable
。示例:
class User: EVObject { # extend EVObject method for the class
var id: Int = 0
var name: String = ""
var friends: [User]? = []
}
# use like below
let json:String = "{\"id\": 24, \"name\": \"Bob Jefferson\", \"friends\": [{\"id\": 29, \"name\": \"Jen Jackson\"}]}"
let user = User(json: json)
示例:
class User: Mappable { # extend Mappable method for the class
var id: Int?
var name: String?
required init?(_ map: Map) {
}
func mapping(map: Map) { # write mapping code
name <- map["name"]
id <- map["id"]
}
}
# use like below
let json:String = "{\"id\": 24, \"name\": \"Bob Jefferson\", \"friends\": [{\"id\": 29, \"name\": \"Jen Jackson\"}]}"
let user = Mapper<User>().map(json)
我尝试开发了一个较小的解决方案,不需要使用继承。但是它没有经过充分测试,目前看起来相当丑陋。
https://github.com/peheje/JsonSerializerSwift
您可以将其传入playground进行测试。例如以下类结构:
//Test nonsense data
class Nutrient {
var name = "VitaminD"
var amountUg = 4.2
var intArray = [1, 5, 9]
var stringArray = ["nutrients", "are", "important"]
}
class Fruit {
var name: String = "Apple"
var color: String? = nil
var weight: Double = 2.1
var diameter: Float = 4.3
var radius: Double? = nil
var isDelicious: Bool = true
var isRound: Bool? = nil
var nullString: String? = nil
var date = NSDate()
var optionalIntArray: Array<Int?> = [1, 5, 3, 4, nil, 6]
var doubleArray: Array<Double?> = [nil, 2.2, 3.3, 4.4]
var stringArray: Array<String> = ["one", "two", "three", "four"]
var optionalArray: Array<Int> = [2, 4, 1]
var nutrient = Nutrient()
}
var fruit = Fruit()
var json = JSONSerializer.toJson(fruit)
print(json)
打印
{"name": "Apple", "color": null, "weight": 2.1, "diameter": 4.3, "radius": null, "isDelicious": true, "isRound": null, "nullString": null, "date": "2015-06-19 22:39:20 +0000", "optionalIntArray": [1, 5, 3, 4, null, 6], "doubleArray": [null, 2.2, 3.3, 4.4], "stringArray": ["one", "two", "three", "four"], "optionalArray": [2, 4, 1], "nutrient": {"name": "VitaminD", "amountUg": 4.2, "intArray": [1, 5, 9], "stringArray": ["nutrients", "are", "important"]}}
/// A generic protocol for creating objects which can be converted to JSON
protocol JSONSerializable {
private var dict: [String: Any] { get }
}
extension JSONSerializable {
/// Converts a JSONSerializable conforming class to a JSON object.
func json() rethrows -> Data {
try JSONSerialization.data(withJSONObject: self.dict, options: nil)
}
}
class User: JSONSerializable {
var id: Int
var name: String
var dict { return ["id": self.id, "name": self.name] }
}
现在:
let user = User(...)
let json = user.json()
注意:如果你想将 json
转换为字符串,非常简单:使用以下代码即可:String(data: json, encoding: .utf8)
以上一些答案完全没问题,但我增加了一个扩展,使其更易读和可用。
extension Encodable {
var convertToString: String? {
let jsonEncoder = JSONEncoder()
jsonEncoder.outputFormatting = .prettyPrinted
do {
let jsonData = try jsonEncoder.encode(self)
return String(data: jsonData, encoding: .utf8)
} catch {
return nil
}
}
}
struct User: Codable {
var id: Int
var name: String
}
let user = User(id: 1, name: "name")
print(user.convertToString!)
//这将打印如下:
{
"id" : 1,
"name" : "name"
}
数据样本:
struct ConfigCreds: Codable { // Codable is important!
// some params
}
var configCreds = ConfigCreds()
var jsonStr: String = ""
// Object -> JSON
configCreds
.asJson()
.onSuccess { jsonStr = $0 }
.onFailure { _ in // any failure code }
// JSON -> object of type "ConfigCreds"
someJsonString
.decodeFromJson(type: ConfigCreds.self)
.onSuccess { configCreds = $0 }
.onFailure { _ in // any failure code }
@available(macOS 10.15, *)
public extension Encodable {
func asJson() -> Result<String, Error>{
JSONEncoder()
.try(self)
.flatMap{ $0.asString() }
}
}
public extension String {
func decodeFromJson<T>(type: T.Type) -> Result<T, Error> where T: Decodable {
self.asData()
.flatMap { JSONDecoder().try(type, from: $0) }
}
}
///////////////////////////////
/// HELPERS
//////////////////////////////
@available(macOS 10.15, *)
fileprivate extension JSONEncoder {
func `try`<T : Encodable>(_ value: T) -> Result<Output, Error> {
do {
return .success(try self.encode(value))
} catch {
return .failure(error)
}
}
}
fileprivate extension JSONDecoder {
func `try`<T: Decodable>(_ t: T.Type, from data: Data) -> Result<T,Error> {
do {
return .success(try self.decode(t, from: data))
} catch {
return .failure(error)
}
}
}
fileprivate extension String {
func asData() -> Result<Data, Error> {
if let data = self.data(using: .utf8) {
return .success(data)
} else {
return .failure(WTF("can't convert string to data: \(self)"))
}
}
}
fileprivate extension Data {
func asString() -> Result<String, Error> {
if let str = String(data: self, encoding: .utf8) {
return .success(str)
} else {
return .failure(WTF("can't convert Data to string"))
}
}
}
fileprivate func WTF(_ msg: String, code: Int = 0) -> Error {
NSError(code: code, message: msg)
}
internal extension NSError {
convenience init(code: Int, message: String) {
let userInfo: [String: String] = [NSLocalizedDescriptionKey:message]
self.init(domain: "FTW", code: code, userInfo: userInfo)
}
}
struct User:Codable{
var id:String?
var name:String?
init(_ id:String,_ name:String){
self.id = id
self.name = name
}
}
let user = User("1","pawan")
do{
let userJson = try JSONEncoder().encode(parentMessage)
}catch{
fatalError("Unable To Convert in Json")
}
let jsonDecoder = JSONDecoder()
do{
let convertedUser = try jsonDecoder.decode(User.self, from: userJson.data(using: .utf8)!)
}catch{
}
不确定是否存在库/框架,但如果您想自动完成并避免手动劳动 :-) ,请使用MirrorType
...
class U {
var id: Int
var name: String
init(id: Int, name: String) {
self.id = id
self.name = name
}
}
extension U {
func JSONDictionary() -> Dictionary<String, Any> {
var dict = Dictionary<String, Any>()
let mirror = reflect(self)
var i: Int
for i = 0 ; i < mirror.count ; i++ {
let (childName, childMirror) = mirror[i]
// Just an example how to check type
if childMirror.valueType is String.Type {
dict[childName] = childMirror.value
} else if childMirror.valueType is Int.Type {
// Convert to NSNumber for example
dict[childName] = childMirror.value
}
}
return dict
}
}
以一个简单的例子来说,它缺乏适当的转换支持,也没有递归... 这只是一个MirrorType
演示...
P.S. 这里使用的是U
,但你将会增强NSManagedObject
,然后就可以转换所有的NSManagedObject
子类了。不需要在所有子类/托管对象中实现这个。
@NSManaged
。也许它是导致问题的原因。在这种情况下,我会用Objective-C编写它,然后从Swift中调用它。 - zrzka