We often process the value as a default value if it could not be decoded from JSON. (Recovering with a default value)
However, doing that might cause a serious problem and hide the actual root cause in the app.
Recovering with a default value is not a bad choice, it's important to know the JSON represents unexpected shape or value before recovering.
let json: JSON
do {
self.id = try json.next("id").getString()
} catch {
print(error)
// We can know why decoding failed from error.
// Not found "id" or "id" found but it was not `string` or something else.
// that's why here recover the value to fill `self.id`
self.id = "unknown"
}JAYSON provides 2 ways of accessing to JSON object.
- Easy access (with dynamic-member-lookup)
let urlString: String? = json[3]?.shot?.images?.hidpi_image?.string- Strict access (with dynamic-member-lookup)
We can know where error was caused. (with JSONError)
let id: String = try json
.next(0)
.next("id")
.getString()
Strict and Scalable JSON library.
And also supports dynamicMemberLookup
Swift 5+ iOS📱, watchOS⌚️, tvOS📺, macOS🖥, Linux✨
let urlString: String? = json[3]?["shot"]?["images"]?["hidpi_image"]?.stringif the value does not exist, throw JSONError
Failed location can be known from JSONError
Get Value (String, Bool, Number)
let id: String = try json
.next(0)
.next("id")
.getString()Using dynamicMemberLookup
let id: String = try json
.next(0)
.next(\.id)
.getString()Using the Decoder can be transformed in a custom object. And, throwable
let imageURL: URL = try json
.next(0)
.next("image")
.next("hidpi_image")
.get {
URL.init(string: try $0.getString())!
}Strict getters
extension JSON {
public func getDictionary() throws -> [String : JSON]
public func getArray() throws -> [JSON]
public func getNumber() throws -> NSNumber
public func getInt() throws -> Int
public func getInt8() throws -> Int8
public func getInt16() throws -> Int16
public func getInt32() throws -> Int32
public func getInt64() throws -> Int64
public func getUInt() throws -> UInt
public func getUInt8() throws -> UInt8
public func getUInt16() throws -> UInt16
public func getUInt32() throws -> UInt32
public func getUInt64() throws -> UInt64
public func getString() throws -> String
public func getBool() throws -> Bool
public func getFloat() throws -> Float
public func getDouble() throws -> Double
}
///
extension JSON {
public func get<T>(_ s: (JSON) throws -> T) rethrows -> T
}Optional Read-only properties😁
extension JSON {
public var dictionary: [String : Any]? { get }
public var array: [Any]? { get }
public var string: String? { get }
public var number: NSNumber? { get }
public var double: Double? { get }
public var float: Float? { get }
public var int: Int? { get }
public var uInt: UInt? { get }
public var int8: Int8? { get }
public var uInt8: UInt8? { get }
public var int16: Int16? { get }
public var uInt16: UInt16? { get }
public var int32: Int32? { get }
public var uInt32: UInt32? { get }
public var int64: Int64? { get }
public var uInt64: UInt64? { get }
public var bool: Bool? { get }
}let jsonData: Data = ...
let json = try JSON(data: jsonData)Use JSONEnvironment to attach application-defined, Sendable context while
parsing. Define keys in your application so JAYSON does not need to know the
meaning or type of values such as request or document identifiers.
private enum RequestIDKey: JSONEnvironmentKey {
typealias Value = String
}
extension JSONEnvironment {
var requestID: String? {
get { self[RequestIDKey.self] }
set { self[RequestIDKey.self] = newValue }
}
}
var environment = JSONEnvironment()
environment.requestID = "request-42" // Use identifiers safe for diagnostics.
do {
let json = try JSON(data: jsonData, environment: environment)
let child = try json.next("user")
print(child.environment.requestID) // "request-42"
} catch let error as JSONError {
print(error.environment?.requestID) // Also available when parsing fails.
}Keyed and indexed access, next, array and dictionary projections, and
JSONError cases that retain a JSON value preserve the environment. Error cases
without an associated JSON value, including invalidJSONObject, return no
environment. Mutating operations retain the receiver's environment. A new JSON
created from an array or dictionary starts with an empty environment unless one
is passed explicitly with init(_:environment:). Environment does not affect
JSON equality, hashing, or serialization. JSON(data:) and JSON(any:)
continue to create values with an empty environment.
let jsonData: Data
let json: Any = try JSONSerialization.jsonObject(with: data, options: [])
let json = try JSON(any: json)let userInfo: [AnyHashable: Any]
let json = try JSON(any: json)let objects: [Any]
let json = try JSON(any: json)In the case of the following try it is not required.
let object: [String : JSON]
let json = JSON(object)let object: [JSON]
let json = JSON(object)let object: [JSONWritableType]
let json = JSON(object)let object: [String : JSONWritableType]
let json = JSON(object)let path = try json
.next(0)
.next("image")
.next("hidpi_image")
.currentPath()
// path => "[0]["image"]["hidpi_image"]"If you have access that does not exist key, throw JSONError.
public enum JSONError: Error {
case notFoundKey(key: String, json: JSON)
case notFoundIndex(index: Int, json: JSON)
case failedToGetString(source: Any, json: JSON)
case failedToGetBool(source: Any, json: JSON)
case failedToGetNumber(source: Any, json: JSON)
case failedToGetArray(source: Any, json: JSON)
case failedToGetDictionary(source: Any, json: JSON)
case decodeError(source: Any, json: JSON, decodeError: Error)
case invalidJSONObject
}example:
do {
let urlString: String = try json
.next("shots")
.next(0)
.next("user")
.next("profile_image")
.next("foo") // ‼️ throw
.getString()
} catch {
print(error)
}Output jsonError
notFoundKey("foo",
json
Path: Root->["shots"][0]["user"]["profile_image"]
SourceType: dictionary
Source:
{
large = "https://...";
medium = "https://...";
small = "https://...";
})
try json
.next(0)
.next("image")
.back() // <---
.next("image")
.next("hidpi_image")let json = try! JSON(data)
struct Shot {
let id: Int
let title: String
let width: Int
let height: Int
let hidpiImageURLString: String?
let normalImageURLString: String
let teaserImageURLString: String
}
do {
let shots: [Shot] = try json.getArray().map { json -> Shot in
let imagesjson = try json.next("images")
return Shot(
id: try json.next("id").getInt(),
title: try json.next("title").getString(),
width: try json.next("width").getInt(),
height: try json.next("height").getInt(),
hidpiImageURLString: try? imagesjson.next("hidpi").getString(),
normalImageURLString: try imagesjson.next("normal").getString(),
teaserImageURLString: try imagesjson.next("teaser").getString()
)
}
print(shots)
} catch {
print(error)
}var json = JSON()
json["id"] = 18737649
json["active"] = true
json["name"] = "muukii"
var images = [String:JSON]()
images["large"] = "http://...foo"
images["medium"] = "http://...bar"
images["small"] = "http://...fuzz"
json["images"] = JSON(images)
let data = try json.data(options: .prettyPrinted)-> data
{
"name" : "muukii",
"active" : true,
"id" : 18737649,
"images" : {
"large" : "http:\/\/...foo",
"small" : "http:\/\/...fuzz",
"medium" : "http:\/\/...bar"
}
}
var json = JSON()
json["String"] = "String"
json["NSString"] = JSON("NSString" as NSString)
json["NSNumber"] = NSNumber(value: 0)
json["Int"] = 64
json["Int8"] = JSON(8 as Int8)
json["Int16"] = JSON(16 as Int16)
json["Int32"] = JSON(32 as Int32)
json["Int64"] = JSON(64 as Int64)
json["UInt"] = JSON(64 as UInt)
json["UInt8"] = JSON(8 as UInt8)
json["UInt16"] = JSON(16 as UInt16)
json["UInt32"] = JSON(32 as UInt32)
json["UInt64"] = JSON(64 as UInt64)
json["Bool_true"] = true
json["Bool_false"] = false
json["Float"] = JSON(1.0 / 3.0 as Float)
json["Double"] = JSON(1.0 / 3.0 as Double)
json["CGFloat"] = JSON(1.0 / 3.0 as CGFloat)json is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod "JAYSON"muukii, muukii.app@gmail.com
json is available under the MIT license. See the LICENSE file for more info.
