如何使用 Swift 可解码协议解码嵌套的 JSON 结构？
How to decode a nested JSON struct with Swift Decodable protocol?
这是我的 JSON
{
"id": 1,
"user": {
"user_name": "Tester",
"real_info": {
"full_name":"Jon Doe"
}
},
"reviews_count": [
{
"count": 4
}
]
}
这是我要保存到的结构（不完整）
struct ServerResponse: Decodable {
var id: String
var username: String
var fullName: String
var reviewCount: Int
enum CodingKeys: String, CodingKey {
case id,
// How do i get nested values?
}
}
我看过 Apple's Documentation 解码嵌套结构，但我仍然不明白如何正确处理 JSON 的不同级别。任何帮助将不胜感激。
而不是用 所有 解码 JSON 所需的密钥进行大 CodingKeys 枚举，我建议将密钥分开对于 每个 的嵌套 JSON 对象，使用嵌套枚举来保留层次结构：
// top-level JSON object keys
private enum CodingKeys : String, CodingKey {
// using camelCase case names, with snake_case raw values where necessary.
// the raw values are what's used as the actual keys for the JSON object,
// and default to the case name unless otherwise specified.
case id, user, reviewsCount = "reviews_count"
// "user" JSON object keys
enum User : String, CodingKey {
case username = "user_name", realInfo = "real_info"
// "real_info" JSON object keys
enum RealInfo : String, CodingKey {
case fullName = "full_name"
}
}
// nested JSON objects in "reviews" keys
enum ReviewsCount : String, CodingKey {
case count
}
}
这样可以更轻松地跟踪 JSON 中每个级别的键。
现在，请记住：
A keyed container is used to decode a JSON object, and is decoded with a CodingKey 符合类型（例如我们上面定义的类型）。
一个unkeyed container用于解码一个JSON数组，并且被解码顺序（即每次调用解码或嵌套的容器方法，它前进到数组中的下一个元素）。请参阅答案的第二部分，了解如何迭代一个。
在使用 container(keyedBy:) 从解码器中获取顶级 keyed 容器后（因为您在顶级有一个 JSON 对象），你可以重复使用这些方法：
nestedContainer(keyedBy:forKey:) 从给定键的对象中获取嵌套对象nestedUnkeyedContainer(forKey:) 从对象中获取给定键的嵌套数组nestedContainer(keyedBy:) 从数组中获取下一个嵌套对象nestedUnkeyedContainer() 从数组中获取下一个嵌套数组
例如：
struct ServerResponse : Decodable {
var id: Int, username: String, fullName: String, reviewCount: Int
private enum CodingKeys : String, CodingKey { /* see above definition in answer */ }
init(from decoder: Decoder) throws {
// top-level container
let container = try decoder.container(keyedBy: CodingKeys.self)
self.id = try container.decode(Int.self, forKey: .id)
// container for { "user_name": "Tester", "real_info": { "full_name": "Jon Doe" } }
let userContainer =
try container.nestedContainer(keyedBy: CodingKeys.User.self, forKey: .user)
self.username = try userContainer.decode(String.self, forKey: .username)
// container for { "full_name": "Jon Doe" }
let realInfoContainer =
try userContainer.nestedContainer(keyedBy: CodingKeys.User.RealInfo.self,
forKey: .realInfo)
self.fullName = try realInfoContainer.decode(String.self, forKey: .fullName)
// container for [{ "count": 4 }] – must be a var, as calling a nested container
// method on it advances it to the next element.
var reviewCountContainer =
try container.nestedUnkeyedContainer(forKey: .reviewsCount)
// container for { "count" : 4 }
// (note that we're only considering the first element of the array)
let firstReviewCountContainer =
try reviewCountContainer.nestedContainer(keyedBy: CodingKeys.ReviewsCount.self)
self.reviewCount = try firstReviewCountContainer.decode(Int.self, forKey: .count)
}
}
示例解码：
let jsonData = """
{
"id": 1,
"user": {
"user_name": "Tester",
"real_info": {
"full_name":"Jon Doe"
}
},
"reviews_count": [
{
"count": 4
}
]
}
""".data(using: .utf8)!
do {
let response = try JSONDecoder().decode(ServerResponse.self, from: jsonData)
print(response)
} catch {
print(error)
}
// ServerResponse(id: 1, username: "Tester", fullName: "Jon Doe", reviewCount: 4)
遍历未加密的容器
考虑到您希望 reviewCount 成为 [Int] 的情况，其中每个元素代表嵌套 JSON 中 "count" 键的值：
"reviews_count": [
{
"count": 4
},
{
"count": 5
}
]
您需要遍历嵌套的非键控容器，在每次迭代时获取嵌套的键控容器，并解码 "count" 键的值。您可以使用 count property of the unkeyed container in order to pre-allocate the resultant array, and then the isAtEnd 属性 遍历它。
例如：
struct ServerResponse : Decodable {
var id: Int
var username: String
var fullName: String
var reviewCounts = [Int]()
// ...
init(from decoder: Decoder) throws {
// ...
// container for [{ "count": 4 }, { "count": 5 }]
var reviewCountContainer =
try container.nestedUnkeyedContainer(forKey: .reviewsCount)
// pre-allocate the reviewCounts array if we can
if let count = reviewCountContainer.count {
self.reviewCounts.reserveCapacity(count)
}
// iterate through each of the nested keyed containers, getting the
// value for the "count" key, and appending to the array.
while !reviewCountContainer.isAtEnd {
// container for a single nested object in the array, e.g { "count": 4 }
let nestedReviewCountContainer = try reviewCountContainer.nestedContainer(
keyedBy: CodingKeys.ReviewsCount.self)
self.reviewCounts.append(
try nestedReviewCountContainer.decode(Int.self, forKey: .count)
)
}
}
}
另一种方法是创建一个与 JSON 紧密匹配的中间模型（借助像 quicktype.io 这样的工具），让 Swift 生成解码它的方法，然后在您的最终数据模型中挑选出您想要的部分：
// snake_case to match the JSON and hence no need to write CodingKey enums
fileprivate struct RawServerResponse: Decodable {
struct User: Decodable {
var user_name: String
var real_info: UserRealInfo
}
struct UserRealInfo: Decodable {
var full_name: String
}
struct Review: Decodable {
var count: Int
}
var id: Int
var user: User
var reviews_count: [Review]
}
struct ServerResponse: Decodable {
var id: String
var username: String
var fullName: String
var reviewCount: Int
init(from decoder: Decoder) throws {
let rawResponse = try RawServerResponse(from: decoder)
// Now you can pick items that are important to your data model,
// conveniently decoded into a Swift structure
id = String(rawResponse.id)
username = rawResponse.user.user_name
fullName = rawResponse.user.real_info.full_name
reviewCount = rawResponse.reviews_count.first!.count
}
}
如果将来它包含超过 1 个值，这还允许您轻松地遍历 reviews_count。
为了解决您的问题，您可以将 RawServerResponse 实现拆分为几个逻辑部分（使用 Swift 5）。
#1。实现属性和所需的编码键
import Foundation
struct RawServerResponse {
enum RootKeys: String, CodingKey {
case id, user, reviewCount = "reviews_count"
}
enum UserKeys: String, CodingKey {
case userName = "user_name", realInfo = "real_info"
}
enum RealInfoKeys: String, CodingKey {
case fullName = "full_name"
}
enum ReviewCountKeys: String, CodingKey {
case count
}
let id: Int
let userName: String
let fullName: String
let reviewCount: Int
}
#2。为id属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
// id
let container = try decoder.container(keyedBy: RootKeys.self)
id = try container.decode(Int.self, forKey: .id)
/* ... */
}
}
#3。为userName属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
/* ... */
// userName
let userContainer = try container.nestedContainer(keyedBy: UserKeys.self, forKey: .user)
userName = try userContainer.decode(String.self, forKey: .userName)
/* ... */
}
}
#4。为fullName属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
/* ... */
// fullName
let realInfoKeysContainer = try userContainer.nestedContainer(keyedBy: RealInfoKeys.self, forKey: .realInfo)
fullName = try realInfoKeysContainer.decode(String.self, forKey: .fullName)
/* ... */
}
}
#5。为reviewCount属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
/* ...*/
// reviewCount
var reviewUnkeyedContainer = try container.nestedUnkeyedContainer(forKey: .reviewCount)
var reviewCountArray = [Int]()
while !reviewUnkeyedContainer.isAtEnd {
let reviewCountContainer = try reviewUnkeyedContainer.nestedContainer(keyedBy: ReviewCountKeys.self)
reviewCountArray.append(try reviewCountContainer.decode(Int.self, forKey: .count))
}
guard let reviewCount = reviewCountArray.first else {
throw DecodingError.dataCorrupted(DecodingError.Context(codingPath: container.codingPath + [RootKeys.reviewCount], debugDescription: "reviews_count cannot be empty"))
}
self.reviewCount = reviewCount
}
}
完成实施
import Foundation
struct RawServerResponse {
enum RootKeys: String, CodingKey {
case id, user, reviewCount = "reviews_count"
}
enum UserKeys: String, CodingKey {
case userName = "user_name", realInfo = "real_info"
}
enum RealInfoKeys: String, CodingKey {
case fullName = "full_name"
}
enum ReviewCountKeys: String, CodingKey {
case count
}
let id: Int
let userName: String
let fullName: String
let reviewCount: Int
}
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
// id
let container = try decoder.container(keyedBy: RootKeys.self)
id = try container.decode(Int.self, forKey: .id)
// userName
let userContainer = try container.nestedContainer(keyedBy: UserKeys.self, forKey: .user)
userName = try userContainer.decode(String.self, forKey: .userName)
// fullName
let realInfoKeysContainer = try userContainer.nestedContainer(keyedBy: RealInfoKeys.self, forKey: .realInfo)
fullName = try realInfoKeysContainer.decode(String.self, forKey: .fullName)
// reviewCount
var reviewUnkeyedContainer = try container.nestedUnkeyedContainer(forKey: .reviewCount)
var reviewCountArray = [Int]()
while !reviewUnkeyedContainer.isAtEnd {
let reviewCountContainer = try reviewUnkeyedContainer.nestedContainer(keyedBy: ReviewCountKeys.self)
reviewCountArray.append(try reviewCountContainer.decode(Int.self, forKey: .count))
}
guard let reviewCount = reviewCountArray.first else {
throw DecodingError.dataCorrupted(DecodingError.Context(codingPath: container.codingPath + [RootKeys.reviewCount], debugDescription: "reviews_count cannot be empty"))
}
self.reviewCount = reviewCount
}
}
用法
let jsonString = """
{
"id": 1,
"user": {
"user_name": "Tester",
"real_info": {
"full_name":"Jon Doe"
}
},
"reviews_count": [
{
"count": 4
}
]
}
"""
let jsonData = jsonString.data(using: .utf8)!
let decoder = JSONDecoder()
let serverResponse = try! decoder.decode(RawServerResponse.self, from: jsonData)
dump(serverResponse)
/*
prints:
▿ RawServerResponse #1 in __lldb_expr_389
- id: 1
- user: "Tester"
- fullName: "Jon Doe"
- reviewCount: 4
*/
也可以用库KeyedCodable我准备的。它将需要更少的代码。让我知道你的想法。
struct ServerResponse: Decodable, Keyedable {
var id: String!
var username: String!
var fullName: String!
var reviewCount: Int!
private struct ReviewsCount: Codable {
var count: Int
}
mutating func map(map: KeyMap) throws {
var id: Int!
try id <<- map["id"]
self.id = String(id)
try username <<- map["user.user_name"]
try fullName <<- map["user.real_info.full_name"]
var reviewCount: [ReviewsCount]!
try reviewCount <<- map["reviews_count"]
self.reviewCount = reviewCount[0].count
}
init(from decoder: Decoder) throws {
try KeyedDecoder(with: decoder).decode(to: &self)
}
}
已经发布了许多好的答案，但是 IMO 还没有描述更简单的方法。
当 JSON 字段名称使用 snake_case_notation 编写时，您仍然可以在 Swift 文件中使用 camelCaseNotation。
你只需要设置
decoder.keyDecodingStrategy = .convertFromSnakeCase
在这 ☝️ 行之后 Swift 将自动匹配从 JSON 到 Swift 模型中的 camelCase 字段的所有 snake_case 字段。
例如
user_name` -> userName
reviews_count -> `reviewsCount
...
这是完整的代码
1。编写模型
struct Response: Codable {
let id: Int
let user: User
let reviewsCount: [ReviewCount]
struct User: Codable {
let userName: String
struct RealInfo: Codable {
let fullName: String
}
}
struct ReviewCount: Codable {
let count: Int
}
}
2。设置解码器
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
3。解码
do {
let response = try? decoder.decode(Response.self, from: data)
print(response)
} catch {
debugPrint(error)
}
- 将 json 文件复制到 https://app.quicktype.io
- Select Swift（如果您使用 Swift 5，请检查 Swift 5 的兼容性开关）
- 使用以下代码解码文件
- 瞧！
let file = "data.json"
guard let url = Bundle.main.url(forResource: "data", withExtension: "json") else{
fatalError("Failed to locate \(file) in bundle.")
}
guard let data = try? Data(contentsOf: url) else{
fatalError("Failed to locate \(file) in bundle.")
}
let yourObject = try? JSONDecoder().decode(YourModel.self, from: data)
这是我的 JSON
{
"id": 1,
"user": {
"user_name": "Tester",
"real_info": {
"full_name":"Jon Doe"
}
},
"reviews_count": [
{
"count": 4
}
]
}
这是我要保存到的结构（不完整）
struct ServerResponse: Decodable {
var id: String
var username: String
var fullName: String
var reviewCount: Int
enum CodingKeys: String, CodingKey {
case id,
// How do i get nested values?
}
}
我看过 Apple's Documentation 解码嵌套结构，但我仍然不明白如何正确处理 JSON 的不同级别。任何帮助将不胜感激。
而不是用 所有 解码 JSON 所需的密钥进行大 CodingKeys 枚举，我建议将密钥分开对于 每个 的嵌套 JSON 对象，使用嵌套枚举来保留层次结构：
// top-level JSON object keys
private enum CodingKeys : String, CodingKey {
// using camelCase case names, with snake_case raw values where necessary.
// the raw values are what's used as the actual keys for the JSON object,
// and default to the case name unless otherwise specified.
case id, user, reviewsCount = "reviews_count"
// "user" JSON object keys
enum User : String, CodingKey {
case username = "user_name", realInfo = "real_info"
// "real_info" JSON object keys
enum RealInfo : String, CodingKey {
case fullName = "full_name"
}
}
// nested JSON objects in "reviews" keys
enum ReviewsCount : String, CodingKey {
case count
}
}
这样可以更轻松地跟踪 JSON 中每个级别的键。
现在，请记住：
A keyed container is used to decode a JSON object, and is decoded with a
CodingKey符合类型（例如我们上面定义的类型）。一个unkeyed container用于解码一个JSON数组，并且被解码顺序（即每次调用解码或嵌套的容器方法，它前进到数组中的下一个元素）。请参阅答案的第二部分，了解如何迭代一个。
在使用 container(keyedBy:) 从解码器中获取顶级 keyed 容器后（因为您在顶级有一个 JSON 对象），你可以重复使用这些方法：
nestedContainer(keyedBy:forKey:)从给定键的对象中获取嵌套对象nestedUnkeyedContainer(forKey:)从对象中获取给定键的嵌套数组nestedContainer(keyedBy:)从数组中获取下一个嵌套对象nestedUnkeyedContainer()从数组中获取下一个嵌套数组
例如：
struct ServerResponse : Decodable {
var id: Int, username: String, fullName: String, reviewCount: Int
private enum CodingKeys : String, CodingKey { /* see above definition in answer */ }
init(from decoder: Decoder) throws {
// top-level container
let container = try decoder.container(keyedBy: CodingKeys.self)
self.id = try container.decode(Int.self, forKey: .id)
// container for { "user_name": "Tester", "real_info": { "full_name": "Jon Doe" } }
let userContainer =
try container.nestedContainer(keyedBy: CodingKeys.User.self, forKey: .user)
self.username = try userContainer.decode(String.self, forKey: .username)
// container for { "full_name": "Jon Doe" }
let realInfoContainer =
try userContainer.nestedContainer(keyedBy: CodingKeys.User.RealInfo.self,
forKey: .realInfo)
self.fullName = try realInfoContainer.decode(String.self, forKey: .fullName)
// container for [{ "count": 4 }] – must be a var, as calling a nested container
// method on it advances it to the next element.
var reviewCountContainer =
try container.nestedUnkeyedContainer(forKey: .reviewsCount)
// container for { "count" : 4 }
// (note that we're only considering the first element of the array)
let firstReviewCountContainer =
try reviewCountContainer.nestedContainer(keyedBy: CodingKeys.ReviewsCount.self)
self.reviewCount = try firstReviewCountContainer.decode(Int.self, forKey: .count)
}
}
示例解码：
let jsonData = """
{
"id": 1,
"user": {
"user_name": "Tester",
"real_info": {
"full_name":"Jon Doe"
}
},
"reviews_count": [
{
"count": 4
}
]
}
""".data(using: .utf8)!
do {
let response = try JSONDecoder().decode(ServerResponse.self, from: jsonData)
print(response)
} catch {
print(error)
}
// ServerResponse(id: 1, username: "Tester", fullName: "Jon Doe", reviewCount: 4)
遍历未加密的容器
考虑到您希望 reviewCount 成为 [Int] 的情况，其中每个元素代表嵌套 JSON 中 "count" 键的值：
"reviews_count": [
{
"count": 4
},
{
"count": 5
}
]
您需要遍历嵌套的非键控容器，在每次迭代时获取嵌套的键控容器，并解码 "count" 键的值。您可以使用 count property of the unkeyed container in order to pre-allocate the resultant array, and then the isAtEnd 属性 遍历它。
例如：
struct ServerResponse : Decodable {
var id: Int
var username: String
var fullName: String
var reviewCounts = [Int]()
// ...
init(from decoder: Decoder) throws {
// ...
// container for [{ "count": 4 }, { "count": 5 }]
var reviewCountContainer =
try container.nestedUnkeyedContainer(forKey: .reviewsCount)
// pre-allocate the reviewCounts array if we can
if let count = reviewCountContainer.count {
self.reviewCounts.reserveCapacity(count)
}
// iterate through each of the nested keyed containers, getting the
// value for the "count" key, and appending to the array.
while !reviewCountContainer.isAtEnd {
// container for a single nested object in the array, e.g { "count": 4 }
let nestedReviewCountContainer = try reviewCountContainer.nestedContainer(
keyedBy: CodingKeys.ReviewsCount.self)
self.reviewCounts.append(
try nestedReviewCountContainer.decode(Int.self, forKey: .count)
)
}
}
}
另一种方法是创建一个与 JSON 紧密匹配的中间模型（借助像 quicktype.io 这样的工具），让 Swift 生成解码它的方法，然后在您的最终数据模型中挑选出您想要的部分：
// snake_case to match the JSON and hence no need to write CodingKey enums
fileprivate struct RawServerResponse: Decodable {
struct User: Decodable {
var user_name: String
var real_info: UserRealInfo
}
struct UserRealInfo: Decodable {
var full_name: String
}
struct Review: Decodable {
var count: Int
}
var id: Int
var user: User
var reviews_count: [Review]
}
struct ServerResponse: Decodable {
var id: String
var username: String
var fullName: String
var reviewCount: Int
init(from decoder: Decoder) throws {
let rawResponse = try RawServerResponse(from: decoder)
// Now you can pick items that are important to your data model,
// conveniently decoded into a Swift structure
id = String(rawResponse.id)
username = rawResponse.user.user_name
fullName = rawResponse.user.real_info.full_name
reviewCount = rawResponse.reviews_count.first!.count
}
}
如果将来它包含超过 1 个值，这还允许您轻松地遍历 reviews_count。
为了解决您的问题，您可以将 RawServerResponse 实现拆分为几个逻辑部分（使用 Swift 5）。
#1。实现属性和所需的编码键
import Foundation
struct RawServerResponse {
enum RootKeys: String, CodingKey {
case id, user, reviewCount = "reviews_count"
}
enum UserKeys: String, CodingKey {
case userName = "user_name", realInfo = "real_info"
}
enum RealInfoKeys: String, CodingKey {
case fullName = "full_name"
}
enum ReviewCountKeys: String, CodingKey {
case count
}
let id: Int
let userName: String
let fullName: String
let reviewCount: Int
}
#2。为id属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
// id
let container = try decoder.container(keyedBy: RootKeys.self)
id = try container.decode(Int.self, forKey: .id)
/* ... */
}
}
#3。为userName属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
/* ... */
// userName
let userContainer = try container.nestedContainer(keyedBy: UserKeys.self, forKey: .user)
userName = try userContainer.decode(String.self, forKey: .userName)
/* ... */
}
}
#4。为fullName属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
/* ... */
// fullName
let realInfoKeysContainer = try userContainer.nestedContainer(keyedBy: RealInfoKeys.self, forKey: .realInfo)
fullName = try realInfoKeysContainer.decode(String.self, forKey: .fullName)
/* ... */
}
}
#5。为reviewCount属性
设置解码策略
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
/* ...*/
// reviewCount
var reviewUnkeyedContainer = try container.nestedUnkeyedContainer(forKey: .reviewCount)
var reviewCountArray = [Int]()
while !reviewUnkeyedContainer.isAtEnd {
let reviewCountContainer = try reviewUnkeyedContainer.nestedContainer(keyedBy: ReviewCountKeys.self)
reviewCountArray.append(try reviewCountContainer.decode(Int.self, forKey: .count))
}
guard let reviewCount = reviewCountArray.first else {
throw DecodingError.dataCorrupted(DecodingError.Context(codingPath: container.codingPath + [RootKeys.reviewCount], debugDescription: "reviews_count cannot be empty"))
}
self.reviewCount = reviewCount
}
}
完成实施
import Foundation
struct RawServerResponse {
enum RootKeys: String, CodingKey {
case id, user, reviewCount = "reviews_count"
}
enum UserKeys: String, CodingKey {
case userName = "user_name", realInfo = "real_info"
}
enum RealInfoKeys: String, CodingKey {
case fullName = "full_name"
}
enum ReviewCountKeys: String, CodingKey {
case count
}
let id: Int
let userName: String
let fullName: String
let reviewCount: Int
}
extension RawServerResponse: Decodable {
init(from decoder: Decoder) throws {
// id
let container = try decoder.container(keyedBy: RootKeys.self)
id = try container.decode(Int.self, forKey: .id)
// userName
let userContainer = try container.nestedContainer(keyedBy: UserKeys.self, forKey: .user)
userName = try userContainer.decode(String.self, forKey: .userName)
// fullName
let realInfoKeysContainer = try userContainer.nestedContainer(keyedBy: RealInfoKeys.self, forKey: .realInfo)
fullName = try realInfoKeysContainer.decode(String.self, forKey: .fullName)
// reviewCount
var reviewUnkeyedContainer = try container.nestedUnkeyedContainer(forKey: .reviewCount)
var reviewCountArray = [Int]()
while !reviewUnkeyedContainer.isAtEnd {
let reviewCountContainer = try reviewUnkeyedContainer.nestedContainer(keyedBy: ReviewCountKeys.self)
reviewCountArray.append(try reviewCountContainer.decode(Int.self, forKey: .count))
}
guard let reviewCount = reviewCountArray.first else {
throw DecodingError.dataCorrupted(DecodingError.Context(codingPath: container.codingPath + [RootKeys.reviewCount], debugDescription: "reviews_count cannot be empty"))
}
self.reviewCount = reviewCount
}
}
用法
let jsonString = """
{
"id": 1,
"user": {
"user_name": "Tester",
"real_info": {
"full_name":"Jon Doe"
}
},
"reviews_count": [
{
"count": 4
}
]
}
"""
let jsonData = jsonString.data(using: .utf8)!
let decoder = JSONDecoder()
let serverResponse = try! decoder.decode(RawServerResponse.self, from: jsonData)
dump(serverResponse)
/*
prints:
▿ RawServerResponse #1 in __lldb_expr_389
- id: 1
- user: "Tester"
- fullName: "Jon Doe"
- reviewCount: 4
*/
也可以用库KeyedCodable我准备的。它将需要更少的代码。让我知道你的想法。
struct ServerResponse: Decodable, Keyedable {
var id: String!
var username: String!
var fullName: String!
var reviewCount: Int!
private struct ReviewsCount: Codable {
var count: Int
}
mutating func map(map: KeyMap) throws {
var id: Int!
try id <<- map["id"]
self.id = String(id)
try username <<- map["user.user_name"]
try fullName <<- map["user.real_info.full_name"]
var reviewCount: [ReviewsCount]!
try reviewCount <<- map["reviews_count"]
self.reviewCount = reviewCount[0].count
}
init(from decoder: Decoder) throws {
try KeyedDecoder(with: decoder).decode(to: &self)
}
}
已经发布了许多好的答案，但是 IMO 还没有描述更简单的方法。
当 JSON 字段名称使用 snake_case_notation 编写时，您仍然可以在 Swift 文件中使用 camelCaseNotation。
你只需要设置
decoder.keyDecodingStrategy = .convertFromSnakeCase
在这 ☝️ 行之后 Swift 将自动匹配从 JSON 到 Swift 模型中的 camelCase 字段的所有 snake_case 字段。
例如
user_name` -> userName
reviews_count -> `reviewsCount
...
这是完整的代码
1。编写模型
struct Response: Codable {
let id: Int
let user: User
let reviewsCount: [ReviewCount]
struct User: Codable {
let userName: String
struct RealInfo: Codable {
let fullName: String
}
}
struct ReviewCount: Codable {
let count: Int
}
}
2。设置解码器
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
3。解码
do {
let response = try? decoder.decode(Response.self, from: data)
print(response)
} catch {
debugPrint(error)
}
- 将 json 文件复制到 https://app.quicktype.io
- Select Swift（如果您使用 Swift 5，请检查 Swift 5 的兼容性开关）
- 使用以下代码解码文件
- 瞧！
let file = "data.json"
guard let url = Bundle.main.url(forResource: "data", withExtension: "json") else{
fatalError("Failed to locate \(file) in bundle.")
}
guard let data = try? Data(contentsOf: url) else{
fatalError("Failed to locate \(file) in bundle.")
}
let yourObject = try? JSONDecoder().decode(YourModel.self, from: data)